There are several variants available based on the same platform, so you might even be able to find something a bit more beefier out there :)
Edit: I've been running a sheevaplug (512mb ram) with ssh, lighttpd, postfix, dovecot, bind and rsync without much trouble for a few users for a long time. RAM usage hasn't been a problem.
There are a few shortcomings like memory.
Thanks for the tip.