Using Apple Mail on OS X 10.4.10. Connecting to our Zimbra via IMAP - zimbra.xxx.edu. Upon the initial launch of Mail, the IMAP will be polled and new Mail is available for viewing. When Mail gets new messages automatically after the first check, or when I manually check for new messages, Mail reports that my password was rejected by zimbra.xxx.edu. I know that the correct password is stored in the keychain, as new Mail is delivered when launching Apple Mail. Sometimes if I hit 'Cancel' six or seven times I will get new Mail anyway.
Any ideas as to what could be causing the password rejection upon subsequent 'get new mail?'