Is there a common authentication mechanism for LDAP and IMAP?
You are somewhat mixing apples and oranges. IMAP is the Internet Messaging Application Protocol and is used for e-mail. As opposed to POP3 (3rd version of the Post Office Protocol), IMAP leaves the e-mail on the server rather than downloading to a client. LDAP is the Lightweight Directory Access Protocol. It is used to access directories, which in some cases are used for authentication. There are IMAP implementations that use LDAP authentication. Among these is Courier-IMAP. And, I'm sure there are others.
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