I have looked in some other posts and see similar questions, but I need very specific instructions on how to fix this. Could someone please help me out?
Probably because your ISP blocks customer computers from sending out mail directly on port 25 because infected machines send out spam. You have to relay through your ISP’s relayhost. When you find out what it is, you can set it in the postfix config, restart postfix and you can mail out.
Okay, mail servers are “shawmail.wp.shawcable.net”. Where do I place this in postfix? Please point me in the right direction with detail where possible.
Well I only use the CLI, not YaST to configure postfix, so if you are not scared of using a text editor…
as root of course, edit /etc/sysconfig/postfix and set RELAYHOST.
SuSEconfig --module postfix
rcpostfix reload
I’m sure you can do this in YaST, but I never bothered to find out how, it was always faster for me this way, and doesn’t break YaST configuration either. This assumes you have not modified main.cf yourself.