NYCPHP Meetup

[Gary Mort]

A bandaid workaround is to use one of the PHP mail packages that 
supports sending through authenticated external SMTP servers.

The same way your PC's mail client sends.

I know Swiftmail supports this, I don't know about others.

It's slower to send that way, however you gain the ability to route the 
mail through multiple mail servers for testing to see if it is your 
local server that is causing the problem, or the program.

You will need SMTP servers that support some form of authentication.

My recollection is Swiftmail was one of the better packages because it 
supported "pop before send" verification, which is what many providers 
setup when they don't have the time to learn the intricacies of 
configuring their email server.