Question : Problem: Why does iPhone connect to Exchange and not Mac Mail?

My iPhone connects to a certain Exchange server without problems.  However, Mac (10.5.5) Mail can't.  I'm using a URL such as webmail.companyname.com in the iPhone with SSL.  If I try that in Mac Mail, it will give an error that the Exchange Server is not responding.  How is it that the iPhone is able to connect?

Answer : Problem: Why does iPhone connect to Exchange and not Mac Mail?

So port 143 is open on the firewall for the email server? Is port 143 open for webmail.companyname.com? Do you know how to check if your iPhone is connecting via IMAP or HTTP? I need to know the answer to that before I can tell you what the difference is. It's under options for the email in the iPhone. Until you say how it connects, I can't tell you the difference.