Note: You are currently viewing documentation for Moodle 3.1. Up-to-date documentation for the latest stable version of Moodle is probably available here: IMAP authentication.
Location: Settings link in Administration > Plugins > Authentication > Manage authentication in 2.0 onwards or Administration > Users > Authentication > Manage authentication in 1.9
IMAP authentication uses a mailing systems IMAP protocol to check for users accounts. This allows direct integrations with technologies such as Microsoft Exchange servers.