I am looking into enabling IMAP on our Exchange 2003, but want to make sure this will not cause issues. Our spam filter (Websense) can use an IMAP enabled mailbox to release some emails if a user is notified and the email is legitimate. I have a couple concerns: 1. POP3 is enabled on the server, I recall once reading that you should not have POP3 and IMAP enabled. I cannot seem to find where I read that or anything confirming or denying this; is this true, no longer true, or never has been true? 2. I want to make sure this does not affect how any of my current or future users will connect using OWA, Outlook, Iphones or Blackberrys. We have some low level users who do not do well with small changes. Would any of these be affected? Thank you! I've searched all over but can't seem to find these answers.

Enabling IMAP service on mailbox server doesn't cause any issue at all. However, if you want to enable IMAP for Internet access on OWA server, you had better enable security protocol for IMAP. The port number for secure POP3 and IMAP to 995 (POP3) or 993 (IMAP);