Email APIs

Sendgrid

Email

A cloud-based SMTP provider that allows you to send emails without having to maintain email servers

A service that provides solutions relating to marketing and/or transactional email and/or SMS

Temporary Email Service

Mandrill

Email

Mandrill is a reliable, scalable, and secure delivery API for transactional emails from websites and applications. It's ideal for sending data-driven transactional emails, including targeted e-commerce and personalized one-to-one messages.

Disposable temporary Email addresses

Postmark Account-level API

Email

Postmark makes sending and receiving email incredibly easy. The Account-level API allows users to configure all Servers, Domains, and Sender Signatures associated with an Account.

API for free email forwarding service

Email API and SMTP for sending transactional and bulk emails, with email testing sandbox for safe development

Postmark API

Email

Postmark makes sending and receiving email incredibly easy.

GraphQL API for creating and managing ephemeral e-mail inboxes

Email verification API

Validate email addresses for deliverability and spam

Email API for developers

ClickSend REST API v3

Email

This is the official API documentation for ClickSend.com Below you will find a current list of the available methods for clicksend. **NOTE**: You will need to create a free account to use the API. You can [**Register Here**](https://dashboard.clicksend.com/#/signup/step1/). # API URL The API should always be accessed over SSL. Base URL: `https://rest.clicksend.com/v3/` # Authentication Basic HTTP authentication should be used in the header. **Either:** `username`: Your API username `password`: Your API key ``` You can get your API credentials by clicking 'API Credentials' on the top right of the dashboard. ``` **OR** `username`: Your account username `password`: Your account password ``` These are the same credentials that you use to login to the dashboard. ``` ### Authorization Header The Authorization header is constructed as follows: 1. Username and password are combined into a string `username:password` 1. The resulting string is then encoded using Base64 encoding 1. The authorization method and a space i.e. "Basic " is then put before the encoded string. For example, if the user uses `Aladdin` as the username and `open sesame` as the password then the header is formed as follows: `Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==` ### PHP Authentication Header Example (using cURL) `curl_setopt($ch, CURLOPT_HTTPHEADER, ['Authorization: Basic ' . base64_encode("$username:$password")]);` # Verbs The API uses restful verbs. | Verb | Description | |---|---| | `GET` | Select one or more items. Success returns `200` status code. | | `POST` | Create a new item. Success returns `200` status code. | | `PUT` | Update an item. Success returns `200` status code. | | `DELETE` | Delete an item. Success returns `200` status code. | # Status Codes The API will respond with one of the following HTTP status codes. | Code | Response | Description | |---|---|---| | `200` | `SUCCESS` | Request completed successfully. | | `400` | `BAD_REQUEST` | The request was invalid or cannot be otherwise served. An accompanying error message will explain further. | | `401` | `UNAUTHORIZED` | Authentication credentials were missing or incorrect. | | `403` | `FORBIDDEN` | The request is understood, but it has been refused or access is not allowed. An accompanying error message will explain why. | | `404` | `NOT_FOUND` | The URI requested is invalid or the resource requested does not exists. | | `405` | `NOT_FOUND` | Method doesn't exist or is not allowed. | | `429` | `TOO_MANY_REQUESTS` | Rate Limit Exceeded. Returned when a request cannot be served due to the application’s rate limit having been exhausted for the resource. See Rate Limiting. | | `500` | `INTERNAL_SERVER_ERROR` | Something is broken | # Application Status Codes The following status codes can be returned in addition to the HTTP status code. For example, when using the Send SMS endpoint: | Response | Description | |---|---| | `SUCCESS` | Message added to queue OK. Use delivery reports to get an update on the delivery status.| | `MISSING_CREDENTIALS` | Not enough information has been supplied for authentication. Please ensure that your Username and Unique Key are supplied in your request.| | `ACCOUNT_NOT_ACTIVATED` | Your account has not been activated.| | `INVALID_RECIPIENT` | The destination mobile number is invalid.| | `THROTTLED` | Identical message body recently sent to the same recipient. Please try again in a few seconds.| | `INVALID_SENDER_ID` | Invalid Sender ID. Please ensure Sender ID is no longer than 11 characters (if alphanumeric), and contains no spaces.| | `INSUFFICIENT_CREDIT` | You have reached the end of your message credits. You will need to purchase more message credits.| | `INVALID_CREDENTIALS` | Your Username or Unique Key is incorrect.| | `ALREADY_EXISTS` | The resource you're trying to add already exists.| | `EMPTY_MESSAGE` | Message is empty.| | `TOO_MANY_RECIPIENTS` | Too many recipients.| | `MISSING_REQUIRED_FIELDS` | Some required fields are missing.| | `INVALID_SCHE

Send emails directly from client-side JavaScript without a backend server

Validate email address to improve deliverability

Validate and detect disposable and temporary email addresses

Prevent users to sign up with temporary email addresses

API for creating temporary email accounts

Disposable inboxes for end-to-end tests that wait for the email and extract OTP codes

Email for AI agents: send email, receive replies as threads, with per-key send limits and approvals

Disposable inboxes for automated email testing, with OTP extraction

Send a test message and get a spam score, 41 checks with RFC citations and a fix plan

Check a domain's SPF, DKIM, DMARC and MX records and get what to fix, with the values to publish