Peter Eisch wrote:
Check out qpsmtpd and use it as an SMTP relay or even run it on your public MX sever. You could even run it under apache if you'd like.
http://www.oreillynet.com/pub/a/sysadmin/2005/09/15/qpsmtpd.html
That thing is perl based but I guess for a small site it won't really matter. Performance is not an issue.