While the iPhone still doesn’t support Exchange-sans-IMAP, Apple has posted a Knowledge Base document explaining how to set up a corporate mail server for IMAP so that you can use iPhone to retrieve your email from that server. Per the document “These key steps will need to be completed by the IT support team or network

administrator to enable access from iPhone to the corporate mail server.”

The procedure requires opening port 993, installing a digital certificate, and opening port 587, 465, or 25 must be opened to allow email to be sent from iPhone: ‘Apple recommends opening 587 as the most reliable, secure port because it requires user authentication.’