Java Catch-All SMTP Proxy

This is an extension to Radim Kolar's 1999 project SMTPProxy ( This small extension allows this proxy to be used to redirect all mails being sent to it to one recipient. This destination recipíent is configured conveniently on the command line. The tool comes in handy for setting up presentation systems that are not actually connected to the internet and where all e-Mails are delivered locally without regard to their actual recipient address.

So, in a demo setting application mail is "sent" to a real e-mail address but still it arrives at the local mailbox.

Example: application sends mail to, the proxy re-routes this to me@laptop.local and sends it to another SMTP listener (i.e. MTA), possibly on the same machine.

Of course this functionality can be obtained with any decent Unix MTA (i.e. Exim, Postfix, ...) with some more or less creative configuration. But this little tool runs on Java and hence also on Windows systems. Together with other Windows SMTP MTAs (try Philip Hazel's Mercury!) you get a full demo system that runs nicely on a Windows presentation laptop.

Off-topc hint: install a Microsoft Loopback network device, give it a fixed IP address (i.e. to circumvent problems with some Windows MTAs and other server processes which fail to run when no network cable is connected.

Load the application archive (source and class files) here (

The CatchAll extension was written by me, Matthias Gärtner. The same license applies to it as to the original package. Use at your own risk. No warranty of any kind.
Seriously. This proxy processes the SMTP dialog line-by-line only. Folding of From: lines in the message headers are not handled properly, for example! Feel free to improve this code, then let me know!

Back to main page. Back to software page.

This page was last changed on August 09th, 2005. © Matthias Gärtner 2005