One of my friends (who has got a domain on my server) his ISP is now blocking port 25 forcing him to use the ISP's SMTP server. Now I could open an extra port in Postfix (master.cf) on my server for him (in this case port 26): Code: 26 inet n - - - - smtpd All he needs to do is set his mail client to use port 26 instead of 25. My question is: Is this safe to do?? Am I not opening something that spammers can use for mail relaying?? I'm using Debian Sarge with ISPconfig.