• Browse to Admin, Login, User registration and login
  • set "Authentication Method" to Tiki and PEAR::Auth
  • Click "Change preferences" at the bottom of the "User registration and login" section

• Browse to Admin, Login, PEAR::Auth
  • set "Auth Type" to IMAP
  • Set "IMAP/POP3/LDAP Host" to be the IP address or hostname of your IMAP server
  • Set "IMAP/POP3/LDAP Port" to 143
  • Click "Change preferences"

Done!

Customizations required for IMAPS/SSL Support highlighted in green below.

• Browse to Admin, Login, User registration and login
  • set "Authentication Method" to Tiki and PEAR::Auth
  • Click "Change preferences" at the bottom of the section

• Browse to Admin, Login, PEAR::Auth
  • set "Auth Type" to IMAP
  • Set "IMAP/POP3/LDAP Host" to be the IP address or hostname of your IMAP server
  • Set "IMAP/POP3/LDAP Port" to 993
  • If your IMAPS certificate is signed by a well-known Certificate Authority:
    • Set "IMAP/POP3 BaseDSN" to /imap/ssl
  • If your IMAPS certificate is self-signed, or if the above setting does not work:
    • Set "IMAP/POP3 BaseDSN" to /imap/ssl/novalidate-cert
• Click "Change preferences" at the bottom of the section

Documentation needed.

Copy/paste from mailing list:
"On your page, in authentication, you are missing IMAP(S), it is a very good and simpler way to authenticate than LDAP. I just implemented it. It uses the same PEAR:Auth library."