Question : Cannot get iPhone to Sync with Exchange Server

I'm having a devil of a time trying to get a user's iPhone to work with Exchange Active Sync. I have followed a number of different sets of instructions, but in the end the iPhone just won't connect to the server. One site gave a list of things to check, and our server did seem to have everything set correctly. But the last tip was to go to the Exchange server address/OMA to check that Outlook Mobile Access is responding. But when I do that, I get this message: "Outlook(R) Mobile Access is supported only on Microsoft(R) Exchange Server 2003. Currently your mailbox is stored on an older version of Exchange server. Please contact your system administrator for additional assistance.". But we are running Exchange 2003. Any idea what could be going on here?

Answer : Cannot get iPhone to Sync with Exchange Server

which comes to the question, are you using a certificate or not?

I believe with the iPhones, if you are not using a certificate, you need to configure the phone as normal, let the phone try to sync the settings and when it fails, there should be an option that in effect tells you to use the settings anyways.  Once you have the configuration in place, you should be able to go into advanced settings and remove the SSL option.  Again, if you are not using SSL on your server.  The iPhones by default want to setup your mail account with SSL.

http://forums.whirlpool.net.au/forum-replies-archive.cfm/1018847.html

this has some info about some utility you can use (just a quick google search)