What LDAP queries are executed and in what sequence in order for IMAP/POP proxy to work?

Issue

What LDAP queries are executed and in what sequence in order for IMAP/POP proxy to work?

Solution

For IMAP/POP proxy to work, the LDAP queries must determine the mail host and login ID as follows:

If user:mailhost returns a value, that value is used.

If no value is returned by the query user:mailhost, and user:routingaddr returns a value, the information to the right of the at (@) sign is used as the destination host for connection. (For example, if user:routingaddr returns user@mailhost.example.com, then mailhost.example.com is taken as the fully qualified domain name of the host to which the proxy attempts connection.)

Once the mailhost is found, the login id is determined by the following sequence of queries:

user:loginid

user:routingaddr

user:publishedname

If user:loginid does not return a value, user@mailhost.example.com is used as loginid, because this is the value returned by user:routingaddr query.