> The CRAM-MD5 method of authentication requires a cleartext password for
> each user. Older accounts on your system could have been created
before > you had cleartext enabled, causing errors when the user tries
> authenticate. Take a look at the vpasswd file, or the user table and
> see if the problematic users follow that pattern (blank
> cleartext password).
The clients experiencing authentication problem do have clear passwds.
They are stored in mysql and I'm able to access this information with
./vuserinfo as well as viewing the DB records. I've reset a number of them
repeatedly. This seems to provide access, though for a limited time.
Additionally, oddly the authentication errors are not recorded in the
'vlog' table in the vpopmail database. I'm able to track the majority of
the errors using SquirrelMails' sql_squirrel_logger plugin.