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Email API

Definition:

An email API gives applications access to an Email Service Provider's (ESP) functionality like receiving, creating, and sending transactional emails, manipulating templates, moving or editing folders, building drafts, etc.

Email APIs can also gives access to email content, attachments, and contacts.

Common ESPs that provide email APIs include Google's Gmail, Outlook, Microsoft Exchange, Microsoft Office 365. There are also email protocols like POP3, SMTP, and IMAP.

There are generally two main categories of email APIs: transactional and contextual.

A transactional email API is designed for bulk emails like mass marketing campaigns or automated routine emails like password resets and signup welcome emails. SendGrid and Mailchimp are examples of transactional email API services.

A contextual email API is designed for developers to build email functionality into their own applications. These email APIs offer features like sync, send, receive, and CRUD operations on email data like email content, folders, and attachments. Kloudless Unified Email API and Nylas are examples of contextual email API services.