Swaks - Swiss Army Knife for SMTP


Swaks is a featureful, flexible, scriptable, transaction-oriented SMTP test tool written and maintained by John Jetmore. It is free to use and licensed under the GNU GPLv2. Features include:

  • SMTP extensions including TLS, authentication, pipelining, PROXY, PRDR, and XCLIENT
  • Protocols including SMTP, ESMTP, and LMTP
  • Transports including UNIX-domain sockets, internet-domain sockets (IPv4 and IPv6), and pipes to spawned processes
  • Completely scriptable configuration, with option specification via environment variables, configuration files, and command line


The latest version of Swaks is 20190914.0, which can be downloaded as a package or a standalone script.

There is also a versions page which lists every released version of Swaks, complete with changelogs and download links.


The reference documentation from the latest release, which includes quick-start examples, is available. There is also an Occasionally Asked Questions document.


The Swaks source code is available at https://github.com/jetmore/swaks.

News (rss)


  • Send a mail to receive email when new versions are released
  • Follow @SwaksSMTP on twitter
  • Contact the author - suggestion, tips, patches, feedback, critiques always welcome
  • Blog - Swaks-specific blog category (same feed as News section above)
  • Issues - Open an issue for feature requests and bugs