We just recently migrated from 7 to 8. Everything appears to be running fine except that now users are unable to send emails from their iPhones. Droids work fine. Just cannot send from an iPhone. The other odd part is that if the iPhone is connected WiFi anywhere where the ISP is the same as us then the email will go through, but not if it is a different ISP.

Ports 587, 995, 25, 110, 443 are all open.

Again, Droids work fine from anywhere. iPhones don't work unless they are WiFi on the same ISP.

Thanks in advance for any assistance. This is REALLY frustrating.