The other discussions I found did not give a clear answer to my question.

Problem description: I am running an embedded Linux server device, such as TuxRail or a DreamPlug which are ARM-based devices with very little of memory and using a micro-SD card as their mass memory device and don't have GUI frontends. They are running Debian Squeeze. I also have IP-cameras from D-Link which can send motion captures via email with SMTP-settings but which have bad limitations (such as that username-field cannot be over 20 characters(!)) and that is why I want to create my own SMTP/eSMTP-server into a separate Linux box which would allow these short usernames and then relay these emails forward to actual ISP's SMTP-server.

Question: What would be suitable "real" SMTP-server for such a Linux SBC box? Your answer is only worthwhile, if the server you suggest runs a daemon which acts as a SMTP server in TCP/IP port 25 and/or 465 and can relay those emails to similar ISP servers.

(Please don't suggest me something completely different from what I asked, I specifically want "IP-to-IP" kind of SMTP relay server, not commandline MTAs or anything like that since I don't have access to the commandline of that IP-camera product)

Thanks in advance!


I would suggest Postfix, especially on Debian where postfix is split into several packages. You can choose and trim features as necessary.

Postfix is powerful, modular, highly secure, lightweight, extensible and easy to configure.

On my VPS with 256MB of RAM, the postfix daemons collectively use about 6.5MB of resident memory which includes TLS and PCRE modules.


I actually like the Postfix answer by bahamat. But there's a hacky alternative too: write a trivial SMTP proxy server (in, say Python) which accepts connections, makes an ongoing connection to a real server, edits the RCPT TO commands before passing them on (to change the email address) and passes all other content through unchanged. Aesthetically unpleasant, but extremely lightweight.

  • If you want to go the python route have a look at docs.python.org/library/smtpd.html – Ulrich Dangel Jun 30 '12 at 0:00
  • I don't know if I'd go for that. Even "hello world" in python has a resident size of 4MB, not including any other modules needed to create a functional MTA. For slightly more you have something that works much better, and with far less effort. – bahamat Jun 30 '12 at 0:41

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