When I started work this past month, my first task was setting up a VPS for the website that will provide other services as well (SVN, mail, etc). Setting up a LAMP server isn't that difficult for me, but I've been totally flummoxed by Sendmail/Postfix/EXIM4.
I'll explain what I've done, and what isn't working. I set up a Ubuntu 10.04 VPS with VPS.net, and use ISPManager to configure many of the services. I set up sendmail initially, but that didn't seem to work, so I moved to POSTFIX which appears to be working better. The server is directly connected to the internet, so I don't want to relay mail anywhere but my system. It seems I can send messages locally without many problems, but I can't get external messages. According to mail.log, messages are queued, and I see the from/to addresses, but doesn't seem to be delivered.
Is there anyone who knows a lot about postfix and Linux configurations that might help? What else should I look at?
Some ISPs don't allow direct outgoing mails from their VPS systems. With those ISPs you need to configure a relay host setting where you define which server of your ISP will handle the outgoing mail. You can test if your ISP blocks outgoing mails by opening an SSH shell on your VPS and issue the command telnet webmasterworld.com 25 If you receive a 220 connect message, then your ISP allows direct outgoing mails and the problem is somewhere in your postfix setup. Otherwise you need to ask your ISP for the proper relay server settings.