I have to confess to a great deal of confusion regarding authentication issues. I am trying to get to a point were I can move Cyrus in to replace an exchange system. I am getting tired of doing recovery of the exchange mailstore when it bin-annually decides to self destruct. Almost all the clients are outlook 2000 using IMAP. Does the IMAP client have to support the authentication method chosen ? I have not read the details of the IMAP spec, but wouldn't Outlook have to support Kerberose to be able to make use of it ? I would like to run Cyrus as a black box on a Linux machine. I do not ca re and would probably prefer if the accounts on the Linux machine had nothing to do with the mail accounts. I would prefer that the mail accounts were authorized against a W2K DC. I am gathering that gives my authentication choices of: PAM NTLM K5 LDAP Or K5 direct from SASL. Since I do not need the IMAP users to validate in any other way on the Linux box, a SASL direct method seems more appropriate than PAM. Which seems to suggest K5. However trying to connect Cyrus via K5 to a W2K DC seems to have an enormous number of unknowns. If the only thing I am using K5 for is Cyrus, do I need any other client or server authentication tools - I.E. Heimdal, or MIT K5 on the Linux box ? Do I need to create a service account on the W2K DC for Cyrus ? Do I need to create a machine account for the Linux box ? After I have all of this working - if that is even possible, is Outlook going to be happy ?