Mailpit

Mailpit is a small, fast, low memory, zero-dependency, multi-platform email testing tool & API for developers. It acts as an SMTP server, provides a modern web interface to view & test captured emails, and includes an API for automated integration testing. Mailpit was originally inspired by MailHog which is no longer maintained and hasn't seen active development or security updates for a few years now. You can forward smtp port 1025 through the port. Currently, Mailpit has been adjusted to a compatibility mode of "accepting any username and password", as long as it complies with the mailbox specification.