I finally have my iPhone syncing successfully with my Exchange 2007 server. You need to do the following Enable IMAP4 port (993) in firewall Enable SMTP port (25) in firewall Enable IMAP service in Exchange 2007 Enable IMAP for the user accounts ( Set-CASMailbox -Identity mailboxname -IMAPEnabled $true ) -The interesting thing is I didn't see IMAP listed in the dialog in the article, but in PowerShell you can see it enabled for the user. Enable SSL for IMAP service. (Much easier if you have IIS SSL Cert Installed Allow "ms-Exch-SMTP-Accept-Any-Recipient" right to the SMTP connector. - In my configuration I have a service that sends anonymous email to my Exchange server. I moved the anonymous concector to port 26 and kept it internal. The external facing connector doesn't allow anonymous access. On the iPhone You need to configure the email address to be and email address of your Exchange domain, otherwise the SMTP connector will reject the emails. Use "Password" authentication and not NTLM...