I am not very good with Linux but CentOS 6 is what I chose to do our intranet with. And it has been awesome for speed and reliability. I have several PHP applications running on it that have been using PHP Mail() to send out notices.
Unfortunately, 3 times our Exchange host has stopped those messages because of changes to settings by the cloud host. Really annoying.
So, I setup my own relay server out on the internet. It has worked for a couple of applications that have a place to create SMTP settings. My real issue is that some just use the PHP Mail() function in several scripts.... how do I point that to my outside SMTP server. Feelin' dumb...
Thanks for any help!