Open Source Go Email Servers

Inbucket is an email testing application; it will accept messages from any email address and make them available to view via a web interface. When you need to test your webapp's outbound emails with Mailinator but are stuck behind a firewall, Inbucket provides the solution. It allows you to keep your new application development secret until it's time to release it. Inbucket is ideal for validating that emails go out as part of your integration test suite, sending links to coworkers to demonstrate an email without sharing your Gmail password, and load testing your application without overwhelming your corporate Exchange server. You can use production data in your test environment without the risk of test messages leaking to an end user, and preview emails in multiple desktop email clients. Use Inbucket for all these needs and more.

Inspired by MailCatcher, easier to install. Built with Go, MailHog runs without installation on multiple platforms. Run it from Docker Hub or using the provided Dockerfile. The SMTP server starts on port 1025, the HTTP server starts on port 8025, in-memory message storage. ESMTP server implementing RFC5321. Support for SMTP AUTH (RFC4954) and PIPELINING (RFC2920). Web interface to view messages (plain text, HTML or source). Supports RFC2047 encoded headers. Real-time updates using EventSource. Release messages to real SMTP servers. Chaos Monkey for failure testing. HTTP API to list, retrieve and delete messages. See APIv1 and APIv2 documentation for more information. HTTP basic authentication for MailHog UI and API. Multipart MIME support. Download individual MIME parts. In-memory message storage. MongoDB and file based storage for message persistence. Lightweight and portable. No installation required.

Mox is a modern email server written in Go that aims to be simple, secure, and standards-compliant. It includes SMTP, IMAP, DMARC, SPF, DKIM, and other protocols required to host email services. Designed for self-hosters and developers who want better control over their email stack, Mox focuses on code clarity, privacy, and correctness, offering a complete mail server solution that is easy to set up and maintain.