ImapKit

ImapKit is a library that runs a strict IMAP server inside a test suite so developers can check how an email client behaves against a real mail protocol. Each test starts a fresh server in milliseconds with the mailboxes, users and extensions it needs, then changes the server while the client is connected, adding messages, changing flags or dropping connections. It supports IMAP4rev1 and IMAP4rev2 with more than 50 extensions including IDLE, CONDSTORE and QRESYNC, rejects input that breaks the standards, and can script late responses, throttling and autologout. It is installed from npm, can also run as a command with a REST API for tests written in Python, Go or other languages, and is released under the MIT licence. The footer names Postal Systems OÜ and the site lists no price. The maker presented it on Hacker News on 8 October 2026. Buyers should note that it is a test tool and not a mail server for real users.

Not yet independently verified: The launch date rests on the maker’s own Show HN post of 8 October 2026, and the domain was registered on 7 October 2026. Every detail comes from the maker’s own site; the company form is shown in the footer without a location, and no independent report was found. We will update this when it can be confirmed, and remove this note.