Ive seen a few similar threads but nothing resolved...

when using php mail(); function it doesn't always work. If I send the email to a domain on my dedicated server it sends perfect. But if I send an email to someone not hosted on my dedicated server they don't receive it...

Any ideas?...

Also I tried to send to a yahoo email account i setup and that did work...

any help would be great!

Do you have reverse DNS for all your mail servers? Many mail servers don't accept mail from mail servers with no reverse DNS entry.

yes I believe I set that up...I can double check

Tail your maillog when trying to send something to see what it says. That'll give a lot of clues as to what is happening.

tail -f /usr/local/psa/var/log/maillog

where do I insert the tail -f/usr/.... part at?

At command line when you SSH into the server.