EmailEngine

EmailEngine is a self-hosted application that opens IMAP and SMTP connections against registered email accounts to translate API requests to IMAP commands, send emails, and monitor changes on these accounts. Whenever a change on the email account is detected – a new email arrives or an existing email is deleted or an unseen message was marked as seen, then EmailEngine sends a webhook notification about it.

EmailEngine is an alternative to rolling custom IMAP handling code. For example, using PHP's IMAP extension only takes you so far; anything more complex than listing the current mailbox state and you're on your own, buried under RFCs and strange edge cases.