I have been trying to setup exchange 2003 emails on Iphone email client using imap and was successful in setting up an email account. But i couldn't setup other two email account on the same phone and password incorrect error keeps coming up. All these three username/email account is a part of the same domain and same OU. The setup did not allow to use SSL and successful email account was added with SSL turned off. Any suggestion would be much appreciated. Thanks.
Been there, done that, got the bald patch to prove it. One issue I've not yet seen documented is a problem when the user logon ID is different to their email alias on Exchange. I had a couple of accounts where the two were different and it was not until I changed either the ID or the alias to match each other that I could get this working.
If you have Exchange You should opt for Exchange ActiveSync, for a variety of reasons including security, push functionality and more sync capabilities.
It is rare to define a port for EAS, if you are on IMAP try this link for a port reference, but you should be getting these settings from your Systems Administrator or internet provider