.NET client documentation

This documentation is for developers interested in using the GOV.UK Notify .NET client to send emails (including documents), text messages or letters. GOV.UK Notify supports .NET framework 4.6.2 and .NET Core 2.0.

Set up the client

Prerequisites

This documentation assumes you are using Microsoft Visual Studio with the NuGet Package Manager.

Refer to the client changelog for the version number and the latest updates.

Install the client

The GOV.UK Notify client can be installed from Nuget.org.

You can install the GOV.UK Notify client package using either the command line or Microsoft Visual Studio.

Warning If you need a version of our API client older than 4.0.0, you should download it from Github [external link]

Use the dotnet command line interface

Go to your project directory and run the following in the command line to install the client package:

dotnet add package GovukNotify

Use Microsoft Visual Studio

Use the NuGet Package Manager to install the GovukNotify client package in Visual Studio.

You can use either the console or the UI.

Console

Run the following in the NuGet package manager console to install the client package:

nuget install GovukNotify

User Interface (UI)

Use the Package Manager UI to search for and install the client package.

Create a new instance of the client

Add this code to your application:

using Notify.Client;
using Notify.Models;
using Notify.Models.Responses;

var client = new NotificationClient(apiKey);

To get an API key, sign in to GOV.UK Notify and go to the API integration page. You can find more information in the API keys section of this documentation.

Connect through a proxy (optional)

If you use a proxy, you must set the proxy configuration in the web.config file. Refer to the Microsoft documentation on proxy configuration for more information.

using Notify.Client;
using Notify.Models;
using Notify.Models.Responses;
using System.Net.Http;

var httpClientWithProxy = new HttpClientWrapper(new HttpClient(...));
var client = new NotificationClient(httpClientWithProxy, apiKey);

Send a message

You can use GOV.UK Notify to send emails, text messages and letters.

Send a text message

Method

SmsNotificationResponse response = client.SendSms(
  mobileNumber: "+447900900123",
  templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a",
  );

Arguments

mobileNumber (required)

The phone number of the recipient of the text message. This can be a UK or international number.

string mobileNumber: "+447900900123";

templateId (required)

To find the template ID:

Sign in to GOV.UK Notify.
Go to the Templates page and select the relevant template.
Select Copy template ID to clipboard.

For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

personalisation (optional)

If a template has placeholder fields for personalised information such as name or reference number, you need to provide their values in a Dictionary. For example:

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    {"first_name", "Amala"},
    {"application_date", "2018-01-01"}
};

You can leave out this argument if a template does not have any placeholder fields for personalised information.

reference (optional)

A unique identifier you can create if you need to. This reference identifies a single unique notification or a batch of notifications. It must not contain any personal information such as name or postal address. For example:

string reference: "STRING";

You can leave out this argument if you do not have a reference.

smsSenderId (optional)

A unique identifier of the sender of the text message notification.

To find the text message sender:

Sign in to GOV.UK Notify.
Go to the Settings page.
In the Text Messages section, select Manage on the Text Message sender row.

You can then either:

copy the sender ID that you want to use and paste it into the method
select Change to change the default sender that the service uses, and select Save

For example:

string smsSenderId: "8e222534-7f05-4972-86e3-17c5d9f894e2";

You can leave out this argument if your service only has one text message sender, or if you want to use the default sender.

Response

If the request to the client is successful, the client returns an SmsNotificationResponse:

public String id;
public String reference;
public String uri;
public Template template;
public SmsResponseContent;

public class Template {
    public String id;
    public String uri;
    public Int32 version;
}
public class SmsResponseContent{
    public string body;
    public string fromNumber;
}

If you use the test API key, all your messages come back with a delivered status.

All messages sent using the team and guest list or live keys appear on your dashboard.

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient using a team-only API key"` `}]`	Use the correct type of API key
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient when service is in trial mode - see https://www.notifications.service.gov.uk/trial-mode"` `}]`	Your service cannot send this notification in trial mode
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`429`	`[{` `"error": "RateLimitError",` `"message": "Exceeded rate limit for key type TEAM/TEST/LIVE of 3000 requests per 60 seconds"` `}]`	Refer to API rate limits for more information
`429`	`[{` `"error": "TooManyRequestsError",` `"message": "Exceeded send limits (LIMIT NUMBER) for today"` `}]`	Refer to service limits for the limit number
`500`	`[{` `"error": "Exception",` `"message": "Internal server error"` `}]`	Notify was unable to process the request, resend your notification

Send an email

Method

EmailNotificationResponse response = client.SendEmail(emailAddress, templateId, personalisation, reference, emailReplyToId);

client.SendEmail(
    emailAddress: "sender@something.com",
    templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a"
);

Arguments

emailAddress (required)

The email address of the recipient. For example:

string emailAddress: "sender@something.com";

templateId (required)

To find the template ID:

Sign in to GOV.UK Notify.
Go to the Templates page and select the relevant template.
Select Copy template ID to clipboard.

For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

personalisation (optional)

If a template has placeholder fields for personalised information such as name or reference number, you need to provide their values in a Dictionary. For example:

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    {"first_name", "Amala"},
    {"application_date", "2018-01-01"},
    // pass in a list and it will appear as bullet points in the message:
    {"required_documents", new List<string> {"passport", "utility bill", "other id"}}
};

You can leave out this argument if a template does not have any placeholder fields for personalised information.

reference (optional)

string reference: "STRING";

You can leave out this argument if you do not have a reference.

oneClickUnsubscribeURL (recommended)

If you send subscription emails you must let recipients opt out of receiving them. Read our Using Notify page for more information about unsubscribe links.

The one-click unsubscribe URL will be added to the headers of your email. Email clients will use it to add an unsubscribe button.

string oneClickUnsubscribeURL : 'https://example.com/unsubscribe.html?opaque=123456789';

The one-click unsubscribe URL must respond to an empty POST request by unsubscribing the user from your emails. You can include query parameters to help you identify the user.

Your unsubscribe URL and response must comply with the guidance specified in Section 3.1 of IETF RFC 8058.

You can leave out this argument if the email being sent is not a subscription email.

Unsubscribe link at the bottom of the email (recommended)

To add an unsubscribe link at the bottom of your email, use square brackets around the link text and round brackets around the URL. Make sure there are no spaces between the brackets or the link will not work.

Use this example if you have a webpage for users to manage their email subscriptions:

[Unsubscribe](https://www.example.gov.uk/unsubscribe)

Your webpage should ask the recipients to confirm that they want to unsubscribe.

If you do not have your own webpage, you can add a ‘mailto’ link to let users send an email to your team instead. For example:

[Unsubscribe](mailto:example@gov.uk?subject=unsubscribe)

The email address should be a shared inbox managed by your team, not your own email address.

emailReplyToId (optional)

This is an email address specified by you to receive replies from your users. You must add at least one reply-to email address before your service can go live.

To add a reply-to email address:

Sign in to GOV.UK Notify.
Go to the Settings page.
In the Email section, select Manage on the Reply-to email addresses row.
Select Add reply-to address.
Enter the email address you want to use, and select Add.

For example:

string emailReplyToId: "8e222534-7f05-4972-86e3-17c5d9f894e2";

You can leave out this argument if your service only has one email reply-to address, or you want to use the default email address.

Response

If the request to the client is successful, the client returns an EmailNotificationResponse:

public String id;
public String reference;
public String oneClickUnsubscribeURL;
public String uri;
public Template template;
public EmailResponseContent content;

public class Template{
    public String id;
    public String uri;
    public Int32 version;
}
public class EmailResponseContent{
  public String fromEmail;
  public String body;
  public String subject;
}

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient using a team-only API key"` `}]`	Use the correct type of API key
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient when service is in trial mode - see https://www.notifications.service.gov.uk/trial-mode"` `}]`	Your service cannot send this notification in trial mode
`400`	`[{` `"error": "BadRequestError",` `"message": "File did not pass the virus scan"` `}]`	The file contains a virus
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information.
`429`	`[{` `"error": "RateLimitError",` `"message": "Exceeded rate limit for key type TEAM/TEST/LIVE of 3000 requests per 60 seconds"` `}]`	Refer to API rate limits for more information
`429`	`[{` `"error": "TooManyRequestsError",` `"message": "Exceeded send limits (LIMIT NUMBER) for today"` `}]`	Refer to daily limits for the limit number
`500`	`[{` `"error": "Exception",` `"message": "Internal server error"` `}]`	Notify was unable to process the request, resend your notification.

Send a file by email

To send a file by email, add a placeholder to the template then upload a file. The placeholder will contain a secure link to download the file.

The links are unique and unguessable. GOV.UK Notify cannot access or decrypt your file.

Your file will be available to download for a default period of 26 weeks (6 months).

To help protect your files you can also:

ask recipients to confirm their email address before downloading
choose the length of time that a file is available to download

Add contact details to the file download page

Sign in to GOV.UK Notify.
Go to the Settings page.
In the Email section, select Manage on the Send files by email row.
Enter the contact details you want to use, and select Save.

Add a placeholder to the template

Sign in to GOV.UK Notify.
Go to the Templates page and select the relevant email template.
Select Edit.
Add a placeholder to the email template using double brackets. For example: “Download your file at: ((link_to_file))”

Your email should also tell recipients how long the file will be available to download.

Upload your file

You can upload the following file types:

CSV (.csv)
image (.jpeg, .jpg, .png)
Microsoft Excel Spreadsheet (.xlsx)
Microsoft Word Document (.doc, .docx)
PDF (.pdf)
text (.json, .odt, .rtf, .txt)

Your file must be smaller than 2MB. Contact the GOV.UK Notify team if you need to send other file types.

Convert the PDF to a byte[].
Pass the byte[] to the personalisation argument.
Call the sendEmail method.

For example:


byte[] documentContents = File.ReadAllBytes("<file path>");

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "name", "Foo" },
    { "link_to_file", NotificationClient.PrepareUpload(documentContents)}
};

Set the filename

To do this you will need version 7.0.0 of the .NET client library, or a more recent version.

You should provide a filename when you upload your file.

The filename should tell the recipient what the file contains. A memorable filename can help the recipient to find the file again later.

The filename must end with a file extension. For example, .csv for a CSV file. If you include the wrong file extension, recipients may not be able to open your file.

If you do not provide a filename for your file, Notify will:

generate a random filename
try to add the correct file extension

If Notify cannot add the correct file extension, recipients may not be able to open your file.


byte[] documentContents = File.ReadAllBytes("<file path>");

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "name", "Foo" },
    { "link_to_file", NotificationClient.PrepareUpload(documentContents, filename = "2023-12-25-daily-report.csv")}
};

Ask recipients to confirm their email address before they can download the file

When a recipient clicks the link in the email you’ve sent them, they have to enter their email address. Only someone who knows the recipient’s email address can download the file.

This security feature is turned on by default.

Turn off email address check (not recommended)

If you do not want to use this feature, you can turn it off on a file-by-file basis.

To do this you will need version 6.1.0 of the .NET client library, or a more recent version.

You should not turn this feature off if you send files that contain:

personally identifiable information
commercially sensitive information
information classified as ‘OFFICIAL’ or ‘OFFICIAL-SENSITIVE’ under the Government Security Classifications policy

To let the recipient download the file without confirming their email address, set the confirmEmailBeforeDownload flag to false.


byte[] documentContents = File.ReadAllBytes("<file path>");

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "name", "Foo" },
    { "link_to_file", NotificationClient.PrepareUpload(documentContents, false, false)}
};

Choose the length of time that a file is available to download

Set the number of weeks you want the file to be available using the retentionPeriod parameter.

To use this feature will need version 6.1.0 of the .NET client library, or a more recent version.

You can choose any value between 1 week and 78 weeks. When deciding this, you should consider:

the need to protect the recipient’s personal information
whether the recipient will need to download the file again later

If you do not choose a value, the file will be available for the default period of 26 weeks (6 months).

Files sent before 12 April 2023 had a longer default period of 78 weeks (18 months).


byte[] documentContents = File.ReadAllBytes("<file path>");

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "name", "Foo" },
    { "link_to_file", NotificationClient.PrepareUpload(documentContents, false, true, "52 weeks")}
};

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient using a team-only API key"` `}]`	Use the correct type of API key
`400`	`[{` `"error": "BadRequestError",` `"message": "Can't send to this recipient when service is in trial mode - see https://www.notifications.service.gov.uk/trial-mode"` `}]`	Your service cannot send this notification in trial mode
`400`	`[{` `"error": "BadRequestError",` `"message": "Unsupported file type '(FILE TYPE)'. Supported types are: '(ALLOWED TYPES)'"` `}]`	Wrong file type. You can only upload .csv, .doc, .docx, .jpeg, .jpg, .odt, .pdf, .png, .rtf, .txt or .xlsx files
`400`	`[{` `"error": "BadRequestError",` "message": "`filename` cannot be longer than 100 characters" `}]`	Choose a shorter filename
`400`	`[{` `"error": "BadRequestError",` "message": "`filename` must end with a file extension. For example, filename.csv" `}]`	Include the file extension in your filename
`400`	`[{` `"error": "BadRequestError",` `"message": "Unsupported value for retention_period '(PERIOD)'. Supported periods are from 1 to 78 weeks."` `}]`	Choose a period between 1 and 78 weeks
`400`	`[{` `"error": "BadRequestError",` `"message": "Unsupported value for confirm_email_before_download: '(VALUE)'. Use a boolean true or false value."` `}]`	Use either true or false
`400`	`[{` `"error": "BadRequestError",` `"message": "File did not pass the virus scan"` `}]`	The file contains a virus
`400`	`[{` `"error": "BadRequestError",` `"message": "Send files by email has not been set up - add contact details for your service at https://www.notifications.service.gov.uk/services/(SERVICE ID)/service-settings/send-files-by-email"` `}]`	See how to add contact details to the file download page
`400`	`[{` `"error": "BadRequestError",` `"message": "Can only send a file by email"` `}]`	Make sure you are using an email template
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information.
`429`	`[{` `"error": "RateLimitError",` `"message": "Exceeded rate limit for key type TEAM/TEST/LIVE of 3000 requests per 60 seconds"` `}]`	Refer to API rate limits for more information
`429`	`[{` `"error": "TooManyRequestsError",` `"message": "Exceeded send limits (LIMIT NUMBER) for today"` `}]`	Refer to service limits for the limit number
`500`	`[{` `"error": "Exception",` `"message": "Internal server error"` `}]`	Notify was unable to process the request, resend your notification.
`N/A`	`File is larger than 2MB`	The file is too big. Files must be smaller than 2MB

Send a letter

When you add a new service it will start in trial mode. You can only send letters when your service is live.

To send Notify a request to go live:

Sign in to GOV.UK Notify.
Go to the Settings page.
In the Your service is in trial mode section, select request to go live.

Method

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "address_line_1", "The Occupier" }, // required
    { "address_line_2", "123 High Street" }, // required
    { "address_line_3", "SW14 6BF" }, // required
      ... // any other optional address lines, or personalisation fields found in your template
};

LetterNotificationResponse response = client.SendLetter(templateId, personalisation, reference);

Arguments

templateId (required)

To find the template ID:

Sign in to GOV.UK Notify.
Go to the Templates page and select the relevant template.
Select Copy template ID to clipboard.

For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

personalisation (required)

The personalisation argument always contains the following parameters for the letter recipient’s address:

address_line_1
address_line_2
address_line_3
address_line_4
address_line_5
address_line_6
address_line_7

The address must have at least 3 lines.

The last line needs to be a real UK postcode or the name of a country outside the UK.

Notify checks for international addresses and will automatically charge you the correct postage.

The postcode personalisation argument has been replaced. If your template still uses postcode, Notify will treat it as the last line of the address.

Any other placeholder fields included in the letter template also count as required parameters. You need to provide their values in a Dictionary. For example:

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    {"address_line_1", "The Occupier"},
    {"address_line_2", "123 High Street"},
    {"address_line_3", "Richmond upon Thames"},
    {"address_line_4", "Middlesex"},
    {"address_line_5", "SW14 6BF"},
    {"first_name", "Amala"},
    {"application_id", "4134325"},
    // pass in a list and it will appear as bullet points in the letter:
    {"required_documents", new List<string> {"passport", "utility bill", "other id"}}
};

reference (optional)

string reference: "STRING";

You can leave out this argument if you do not have a reference.

Response

If the request to the client is successful, the client returns a LetterNotificationResponse:

public String id;
public String reference;
public String uri;
public Template template;
public string postage;
public LetterResponseContent content;

public class Template
{
    public String id;
    public String uri;
    public Int32 version;
}
public class LetterResponseContent{
    public string body;
    public string subject;
}

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`403`	`[{` `"error": "BadRequestError",` `"message": "Cannot send letters with a team api key"` `}]`	Use the correct type of API key.
`400`	`[{` `"error": "BadRequestError",` `"message": "Cannot send letters when service is in trial mode - see https://www.notifications.service.gov.uk/trial-mode"` `}]`	Your service cannot send this notification in trial mode.
`400`	`[{` `"error": "ValidationError",` `"message": "personalisation address_line_1 is a required property"` `}]`	Ensure that your template has a field for the first line of the address, refer to personalisation for more information.
`400`	`[{` `"error": "ValidationError",` `"message": "Must be a real UK postcode"` `}]`	Ensure that the value for the last line of the address is a real UK postcode.
`400`	`[{` `"error": "ValidationError",` `"message": "Last line of address must be a real UK postcode or another country"` `}]`	Ensure that the value for the last line of the address is a real UK postcode or the name of a country outside the UK.
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock.
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information.
`429`	`[{` `"error": "RateLimitError",` `"message": "Exceeded rate limit for key type TEAM/TEST/LIVE of 3000 requests per 60 seconds"` `}]`	Refer to API rate limits for more information.
`429`	`[{` `"error": "TooManyRequestsError",` `"message": "Exceeded send limits (LIMIT NUMBER) for today"` `}]`	Refer to service limits for the limit number.
`500`	`[{` `"error": "Exception",` `"message": "Internal server error"` `}]`	Notify was unable to process the request, resend your notification.

Send a precompiled letter

Method

LetterNotificationsResponse response = client.SendPrecompiledLetter(
    clientReference,
    pdfContents,
    postage
    );

Arguments

clientReference (required)

A unique identifier you create. This reference identifies a single unique notification or a batch of notifications. It must not contain any personal information such as name or postal address.

pdfContents (required for the SendPrecompiledLetter method)

The precompiled letter must be a PDF file which meets the GOV.UK Notify letter specification. The method sends the contents of the file to GOV.UK Notify.

byte[] pdfContents = File.ReadAllBytes("<PDF file path>");

postage (optional)

You can choose first or second class postage for your precompiled letter. Set the value to first for first class, or second for second class. If you do not pass in this argument, the postage will default to second class.

Response

If the request to the client is successful, the client returns a LetterNotificationResponse with the id, reference and postage:

public String id;
public String reference;
public String postage;
public String uri;  // null for this response
public Template template;  // null for this response
public LetterResponseContent content;  // null for this response

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`403`	`[{` `"error": "BadRequestError",` `"message": "Cannot send letters with a team api key"` `}]`	Use the correct type of API key
`400`	`[{` `"error": "BadRequestError",` `"message": "Cannot send letters when service is in trial mode - see https://www.notifications.service.gov.uk/trial-mode"` `}]`	Your service cannot send this notification in trial mode
`400`	`[{` `"error": "ValidationError",` `"message": "personalisation address_line_1 is a required property"` `}]`	Send a valid PDF file
`400`	`[{` `"error": "ValidationError",` `"message": "reference is a required property"` `}]`	Add a `reference` argument to the method call
`400`	`[{` `"error": "ValidationError",` `"message": "postage invalid. It must be either first or second."` `}]`	Change the value of `postage` argument in the method call to either ‘first’ or ‘second’
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`429`	`[{` `"error": "RateLimitError",` `"message": "Exceeded rate limit for key type TEAM/TEST/LIVE of 3000 requests per 60 seconds"` `}]`	Refer to API rate limits for more information
`429`	`[{` `"error": "TooManyRequestsError",` `"message": "Exceeded send limits (LIMIT NUMBER) for today"` `}]`	Refer to service limits for the limit number
N/A	`"message":"precompiledPDF must be a valid PDF file"`	Send a valid PDF file
N/A	`"message":"reference cannot be null or empty"`	Populate the reference parameter
N/A	`"message":"precompiledPDF cannot be null or empty"`	Send a PDF file with data in it

Get message status

Get the status of one message

You can only get the status of messages sent within the retention period. The default retention period is 7 days.

Method

Notification notification = client.GetNotificationById(notificationId);

Arguments

notificationId (required)

The ID of the notification. To find the notification ID, you can either:

check the response to the original notification method call
sign in to GOV.UK Notify and go to the API integration page

Response

If the request to the client is successful, the client returns a Notification.

public String id;
public String completedAt;
public String createdAt;
public String emailAddress;
public String body;
public String subject;
public String line1;
public String line2;
public String line3;
public String line4;
public String line5;
public String line6;
public String line7;
public String phoneNumber;
public String postage;
public String reference;
public String sentAt;
public String status;
public Template template;
public String type;
public string createdByName;
public bool isCostDataReady;  
public double costInPounds;
public CostDetails costDetails; 

public class Template
{
    public String id;
    public String uri;
    public Int32 version;
}

public class CostDetails
{
    [JsonProperty("billable_sms_fragments")]
    public int? billableSmsFragments;

    [JsonProperty("international_rate_multiplier")]
    public double? internationalRateMultiplier;

    [JsonProperty("sms_rate")]
    public double? smsRate;

    [JsonProperty("billable_sheets_of_paper")]
    public int? billableSheetsOfPaper;

    public string postage;
}

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "ValidationError",` `"message": "id is not a valid UUID"` `}]`	Check the notification ID
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`404`	`[{` `"error": "NoResultFound",` `"message": "No result found"` `}]`	Check the notification ID

Get the status of multiple messages

This API call returns the status of multiple messages. You can get either the most recent messages, or get older messages by specifying a particular notification ID in the olderThanId argument.

You can only get messages that are 7 days old or newer.

Method

NotificationList notifications = client.GetNotifications(templateType, status, reference, olderThanId, includeSpreadsheetUploads);

Arguments

You can leave out these arguments to ignore these filters.

templateType (optional)

You can filter by:

email
sms
letter

status (optional)

You can filter by each:

email status
text message status
letter status
precompiled letter status

You can leave out this argument to ignore this filter.

reference (optional)

string reference = "STRING";

olderThanId (optional)

Input the ID of a notification into this argument to return the next 250 received notifications older than the given ID. For example:

string olderThanId: "e194efd1-c34d-49c9-9915-e4267e01e92e";

If you leave out this argument, the client returns the most recent 250 notifications.

The client only returns notifications that are 7 days old or newer. If the notification specified in this argument is older than 7 days, the client returns an empty response.

includeSpreadsheetUploads (optional)

Specifies whether the response should include notifications which were sent by uploading a spreadsheet of recipients to Notify.

bool includeSpreadsheetUploads = true;

If you do not pass in this argument it defaults to false.

Response

If the request to the client is successful, the client returns a NotificationList.

public List<Notification> notifications;
public Link links;

public class Link {
    public String current;
    public String next;
}

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "ValidationError",` `"message": "bad status is not one of [created, sending, delivered, pending, failed, technical-failure, temporary-failure, permanent-failure]"` `}]`	Contact the GOV.UK Notify team
`400`	`[{` `"error": "ValidationError",` `"message": "Apple is not one of [sms, email, letter]"` `}]`	Contact the GOV.UK Notify team
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information

Email status descriptions

Status	Description
`created`	GOV.UK Notify has placed the message in a queue, ready to be sent to the provider. It should only remain in this state for a few seconds.
`sending`	GOV.UK Notify has sent the message to the provider. The provider will try to deliver the message to the recipient for up to 72 hours. GOV.UK Notify is waiting for delivery information.
`delivered`	The message was successfully delivered.
`permanent-failure`	The provider could not deliver the message because the email address was wrong. You should remove these email addresses from your database.
`temporary-failure`	The provider could not deliver the message. This can happen when the recipient’s inbox is full or their anti-spam filter rejects your email. Check your content does not look like spam before you try to send the message again.
`technical-failure`	Your message was not sent because there was a problem between Notify and the provider. You’ll have to try sending your messages again.

Text message status descriptions

Status	Description
`created`	GOV.UK Notify has placed the message in a queue, ready to be sent to the provider. It should only remain in this state for a few seconds.
`sending`	GOV.UK Notify has sent the message to the provider. The provider will try to deliver the message to the recipient for up to 72 hours. GOV.UK Notify is waiting for delivery information.
`pending`	GOV.UK Notify is waiting for more delivery information. GOV.UK Notify received a callback from the provider but the recipient’s device has not yet responded. Another callback from the provider determines the final status of the text message.
`sent`	The message was sent to an international number. The mobile networks in some countries do not provide any more delivery information. The GOV.UK Notify website displays this status as ‘Sent to an international number’.
`delivered`	The message was successfully delivered. If a recipient blocks your sender name or mobile number, your message will still show as delivered.
`permanent-failure`	The provider could not deliver the message. This can happen if the phone number was wrong or if the network operator rejects the message. If you’re sure that these phone numbers are correct, you should contact GOV.UK Notify support. If not, you should remove them from your database. You’ll still be charged for text messages that cannot be delivered.
`temporary-failure`	The provider could not deliver the message. This can happen when the recipient’s phone is off, has no signal, or their text message inbox is full. You can try to send the message again. You’ll still be charged for text messages to phones that are not accepting messages.
`technical-failure`	Your message was not sent because there was a problem between Notify and the provider. You’ll have to try sending your messages again. You will not be charged for text messages that are affected by a technical failure.

Letter status descriptions

Status	Description
`accepted`	GOV.UK Notify has sent the letter to the provider to be printed.
`received`	The provider has printed and dispatched the letter.
`cancelled`	Sending cancelled. The letter will not be printed or dispatched.
`technical-failure`	GOV.UK Notify had an unexpected error while sending the letter to our printing provider.
`permanent-failure`	The provider cannot print the letter. Your letter will not be dispatched.

Precompiled letter status descriptions

Status	Description
`accepted`	GOV.UK Notify has sent the letter to the provider to be printed.
`received`	The provider has printed and dispatched the letter.
`cancelled`	Sending cancelled. The letter will not be printed or dispatched.
`pending-virus-check`	GOV.UK Notify has not completed a virus scan of the precompiled letter file.
`virus-scan-failed`	GOV.UK Notify found a potential virus in the precompiled letter file.
`validation-failed`	Content in the precompiled letter file is outside the printable area. See the GOV.UK Notify letter specification for more information.
`technical-failure`	GOV.UK Notify had an unexpected error while sending the letter to our printing provider.
`permanent-failure`	The provider cannot print the letter. Your letter will not be dispatched.

Get a PDF for a letter notification

Method

This returns the pdf contents of a letter notification.

byte[] pdfFile = client.GetPdfForLetter(notificationId);

Arguments

notificationId (required)

The ID of the notification. To find the notification ID, you can either:

check the response to the original notification method call
sign in to GOV.UK Notify and go to the API integration page

Response

If the request to the client is successful, the client will return a byte[] object containing the raw PDF data.

Error codes

If the request is not successful, the client returns a NotificationClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "ValidationError",` `"message": "id is not a valid UUID"` `}]`	Check the notification ID
`400`	`[{` `"error": "ValidationError",` `"message": "Notification is not a letter"` `}]`	Check that you are looking up the correct notification
`400`	`[{` `"error": "PDFNotReadyError",` `"message": "PDF not available yet, try again later"` `}]`	Wait for the notification to finish processing. This usually takes a few seconds
`400`	`[{` `"error": "BadRequestError",` `"message": "File did not pass the virus scan"` `}]`	You cannot retrieve the contents of a letter notification that contains a virus
`400`	`[{` `"error": "BadRequestError",` `"message": "PDF not available for letters in technical-failure"` `}]`	You cannot retrieve the contents of a letter notification in technical-failure
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`404`	`[{` `"error": "NoResultFound",` `"message": "No result found"` `}]`	Check the notification ID

Get a template

Get a template by ID

Method

This returns the latest version of the template.

TemplateResponse response = client.GetTemplateById(
    "templateId"
);

Arguments

templateId (required)

The ID of the template. Sign in to GOV.UK Notify and go to the Templates page to find it. For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

Response

If the request to the client is successful, the client returns a TemplateResponse.

public String id;
public String name;
public String type;
public DateTime created_at;
public DateTime? updated_at;
public String created_by;
public int version;
public String body;
public String subject; // null if an sms message
public String letter_contact_block; // null if not a letter template or contact block not set for letter

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "ValidationError",` `"message": "id is not a valid UUID"` `}]`	Check the notification ID
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`404`	`[{` `"error": "NoResultFound",` `"message": "No Result Found"` `}]`	Check your template ID

Get a template by ID and version

Method

TemplateResponse response = client.GetTemplateByIdAndVersion(
    "templateId",
    1   // integer required for version number
);

Arguments

templateId (required)

The ID of the template. Sign in to GOV.UK Notify and go to the Templates page to find it. For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

version (required)

The version number of the template.

Response

If the request to the client is successful, the client returns a TemplateResponse.

public String id;
public String name;
public String type;
public DateTime created_at;
public DateTime? updated_at;
public String created_by;
public int version;
public String body;
public String subject; // null if an sms message
public String letter_contact_block; // null if not a letter template or contact block not set for letter

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "ValidationError",` `"message": "id is not a valid UUID"` `}]`	Check the notification ID
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information
`404`	`[{` `"error": "NoResultFound",` `"message": "No Result Found"` `}]`	Check your template ID and version

Get all templates

Method

This returns the latest version of all templates.

TemplateList response = client.GetAllTemplates(
    "sms" | "email" | "letter" // optional
);

Arguments

templateType (optional)

If left out, the method returns all templates. Otherwise you can filter by:

email
sms
letter

Response

If the request to the client is successful, the client returns a TemplateList.

List<TemplateResponse> templates;

If no templates exist for a template type or there no templates for a service, the client returns a TemplateList with an empty templates list element:

List<TemplateResponse> templates; // empty list of templates

Generate a preview template

Method

This generates a preview version of a template.

TemplatePreviewResponse response = client.GenerateTemplatePreview(
    templateId,
    personalisation
);

The parameters in the personalisation argument must match the placeholder fields in the actual template. The API notification client ignores any extra fields in the method.

Arguments

templateId (required)

The ID of the template. Sign in to GOV.UK Notify and go to the Templates page to find it. For example:

string templateId: "f33517ff-2a88-4f6e-b855-c550268ce08a";

personalisation (required)

If a template has placeholder fields for personalised information such as name or reference number, you need to provide their values in a Dictionary. For example:

Dictionary<String, dynamic> personalisation = new Dictionary<String, dynamic>
{
    { "name", "someone" }
};

You can leave out this argument if a template does not have any placeholder fields for personalised information.

Response

If the request to the client is successful, you receive a TemplatePreviewResponse response.

public String id;
public String type;
public int version;
public String body;
public String subject; // null if a sms message

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`400`	`[{` `"error": "BadRequestError",` `"message": "Missing personalisation: [PERSONALISATION FIELD]"` `}]`	Check that the personalisation arguments in the method match the placeholder fields in the template
`400`	`[{` `"error": "NoResultFound",` `"message": "No result found"` `}]`	Check the template ID
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information

Get received text messages

This API call returns one page of up to 250 received text messages. You can get either the most recent messages, or get older messages by specifying a particular notification ID in the olderThanId argument.

You can only get the status of messages that are 7 days old or newer.

You can also set up callbacks for received text messages.

Enable received text messages

To receive text messages:

Go to the Text message settings section of the Settings page.
Select Change on the Receive text messages row.

Get a page of received text messages

Method

ReceivedTextListResponse response = client.GetReceivedTexts(olderThanId);

Arguments

olderThanId (optional)

Input the ID of a notification into this argument to return the next 250 received notifications older than the given ID. For example:

olderThanId: "740e5834-3a29-46b4-9a6f-16142fde533a"

If you leave out the olderThanId argument, the client returns the most recent 250 notifications.

The client only returns notifications that are 7 days old or newer. If the notification specified in this argument is older than 7 days, the client returns an empty ReceivedTextListResponse response.

Response

If the request to the client is successful, the client returns a ReceivedTextListResponse that returns all received text messages.

public List<ReceivedText> receivedTextList;
public Link links;

public class Link {
           public String current;
           public String next;
}

public String id;
public String userNumber;
public String createdAt;
public String serviceId;
public String notifyNumber;
public String content;

If the notification specified in the olderThanId argument is older than 7 days, the client returns an empty ReceivedTextListResponse response.

Error codes

If the request is not successful, the client returns a Notify.Exceptions.NotifyClientException containing the relevant error code.

Status code	Message	How to fix
`403`	`[{` `"error": "AuthError",` `"message": "Error: Your system clock must be accurate to within 30 seconds"` `}]`	Check your system clock
`403`	`[{` `"error": "AuthError",` `"message": "Invalid token: API key not found"` `}]`	Use the correct API key. Refer to API keys for more information

Error messages

Error messages consist of:

a status_code, for example ‘400’
an error, for example ’BadRequestError’
a message, for example ‘Mobile numbers can only include: 0 1 2 3 4 5 6 7 8 9 ( ) + -‘

Do not use the content of the messages in your code. These can sometimes change, which may affect your API integration.

Use the status_code or the error instead, as these will not change.

Find error codes in:

send a message
get message status
get a template
get received text messages

Testing

All testing takes place in the production environment. There is no test environment for GOV.UK Notify.

Smoke testing

If you need to smoke test your integration with Notify on a regular basis, you must use the following smoke test phone numbers and email addresses.

Phone numbers

07700900000
07700900111
07700900222

Email addresses

simulate-delivered@notifications.service.gov.uk
simulate-delivered-2@notifications.service.gov.uk
simulate-delivered-3@notifications.service.gov.uk

The smoke test phone numbers and email addresses will validate the request and simulate a successful response, but will not send a real message, produce a delivery receipt or persist the notification to the database.

You can use these smoke test numbers and addresses with any type of API key.

You can smoke test all Notify API client functions except:

Get the status of one message
Get the status of all messages

You cannot use the smoke test phone numbers or email address with these functions because they return a fake notification_ID. If you need to test these functions, use a test API key and any other phone number or email.

Other testing

You must use a test API key to do non-smoke testing such as performance or integration testing. You can use any non-smoke testing phone numbers or email addresses. You do not need a specific Notify testing account.

API keys

There are three different types of API keys:

test
team and guest list
live

When you set up a new service it will start in trial mode. A service in trial mode can create test and team and guest list keys. You must have a live service to create a live key.

To create an API key:

Sign in to GOV.UK Notify.
Go to the API integration page.
Select API keys.
Select Create an API key.

Test

Use a test key to test the performance of your service and its integration with GOV.UK Notify.

Messages sent using a test key:

generate realistic responses
result in a delivered status
are not actually delivered to a recipient
do not appear on your dashboard
do not count against your text message and email allowances

To test failure responses with a test key, use the following numbers and addresses:

Phone number/Email address	Response
07700900003	`temporary-failure`
07700900002	`permanent-failure`
temp-fail@simulator.notify	`temporary-failure`
perm-fail@simulator.notify	`permanent-failure`
any other valid number or address	`delivered`

You do not have to revoke test keys.

Team and guest list

A team and guest list key lets you send real messages to your team members and addresses/numbers on your guest list while your service is still in trial mode.

You will get an error if you use these keys to send messages to anyone who is not on your team or your guest list.

Messages sent with a team and guest list key appear on your dashboard and count against your text message and email allowances.

You do not have to revoke team and guest list keys.

Live

You can only create live keys once your service is live. You can use live keys to send messages to anyone.

Messages sent with a live key appear on your dashboard and count against your text message and email allowances.

You should revoke and re-create these keys on a regular basis. To revoke a key:

Sign in to GOV.UK Notify.
Go to the API integration page.
Select API keys.
Select Revoke for the API key you want to revoke.

You can have more than one active key at a time.

You should never send test messages to invalid numbers or addresses using a live key.

Limits

Rate limits

You’re limited to sending 3,000 messages per minute.

This limit is calculated on a rolling basis, per API key type. If you exceed the limit, you will get a 429 error RateLimitError.

Daily limits

There’s a limit to the number of messages you can send each day:

Service status	Type of API key	Daily limit
Live	Team or live	250,000 emails 250,000 text messages 20,000 letters
Trial	Team	50 emails or text messages
Live or trial	Test	Unlimited

These limits reset at midnight UTC.

Phone network limits

If you repeatedly send text messages to the same number the phone networks will block them.

There’s an hourly limit of:

20 messages with the same content
100 messages with any content

Your messages may not be delivered if you exceed these limits.

Callbacks

Callbacks are when GOV.UK Notify sends POST requests to your service. You can get callbacks when:

a text message or email you’ve sent is delivered or fails
your service receives a text message

Set up callbacks

You must provide:

a URL where Notify will post the callback to
a bearer token which Notify will put in the authorisation header of the requests

To do this:

Sign in to GOV.UK Notify.
Go to the API integration page.
Select Callbacks.

Retry callbacks

If Notify sends a POST request to your service, but the request fails then we will retry.

We will retry every 5 minutes, up to a maximum of 5 times.

Delivery receipts

When you send an email or text message, Notify will send a receipt to your callback URL with the status of the message. This is an automated method to get the status of messages.

This functionality works with test API keys, but does not work with smoke testing phone numbers or email addresses.

The callback message is formatted in JSON. All of the values are strings, apart from the template version, which is a number. The key, description and format of the callback message arguments will be:

Key	Description	Format
`id`	Notify’s id for the status receipts	UUID
`reference`	The reference sent by the service	`12345678` or null
`to`	The email address or phone number of the recipient	`hello@gov.uk` or `07700912345`
`status`	The status of the notification	`delivered`, `permanent-failure`, `temporary-failure` or `technical-failure`
`created_at`	The time the service sent the request	`2017-05-14T12:15:30.000000Z`
`completed_at`	The last time the status was updated	`2017-05-14T12:15:30.000000Z` or null
`sent_at`	The time the notification was sent	`2017-05-14T12:15:30.000000Z` or null
`notification_type`	The notification type	`email` or `sms`
`template_id`	The id of the template that was used	UUID
`template_version`	The version number of the template that was used	`1`

Received text messages

If your service receives text messages in Notify, Notify can forward them to your callback URL as soon as they arrive.

Find out how to let people send text messages to your service.

The callback message is formatted in JSON. All of the values are strings. The key, description and format of the callback message arguments will be:

Key	Description	Format
`id`	Notify’s id for the received message	UUID
`source_number`	The phone number the message was sent from	447700912345
`destination_number`	The number the message was sent to (your number)	07700987654
`message`	The received message	Hello Notify!
`date_received`	The UTC datetime that the message was received by Notify	2017-05-14T12:15:30.000000Z

API architecture

Architecture for sending a text message

The service sends a text message notification to Notify.
Notify sends the text message to the provider.
The provider delivers the text message to the recipient.
The recipient receives the text message and sends a delivery receipt to the provider.
The provider sends the delivery receipt to Notify.
Notify receives the delivery receipt and sends an API response to the service.
The service receives the API response.

Architecture for sending an email

The service sends an email notification to Notify.
Notify sends the email to the provider.
The provider delivers the email to the recipient.
The recipient receives the email and sends a delivery receipt to the provider.
The provider sends the delivery receipt to Notify.
Notify receives the delivery receipt and sends an API response to the service.
The service receives the API response.

Architecture for sending a letter

The service sends a letter notification to Notify.
Notify sends the letter to the provider.
The provider prints the letter and posts it.
The postal service delivers the letter.
The recipient receives the letter.

Architecture for getting the status of a message

The service requests a notification status from Notify.
Notify queries the database and retrieves the notification status.
Notify sends the API response with the notification status to the service.
The service receives the API response.

Architecture for getting received text messages

Recipients send text messages.
Notify receives the text messages.
The service requests all or specific received text messages from Notify.
Notify receives the request for received text messages.
Notify sends the received text messages to the service.
The service receives the received text messages.