From http://forums.cpanel.net/f43/account-based-email-login-problem-97109.html
root@servername [/home]# authtest -s imap test@normaldomain.info password
Authentication succeeded.
Authenticated: test@normaldomain.info (system username: normaldo)
Home Directory: /home/normaldo/mail/normaldomain.info/test
Maildir: /home/normaldo/mail/normaldomain.info/test
Quota: 262144000S
Encrypted Password: $1$KHntyoqN$wih5o0N7ZTf6Fm4vasrxj.
Cleartext Password: password
Options: (none)
FOR MY PROBLEMATIC DOMAIN:::
root@servername [/home]# authtest -s imap info@problemdomain.info password
Authentication FAILED: Operation not permitted
What you want to do next is check /usr/local/cpanel/logs/login_log to see what the exact issue is. In my circumstance, I received this error:
208.74.121.102 - info@jurnamakelaars.nl [10/04/2009:14:37:11 -0000] "POST /login/ HTTP/1.1" FAILED LOGIN webmaild: user password hash is missing from system (user probably does not exist)
I then checked the user’s shadow file in /home/USERNAME/etc/domain.com/shadow and saw that it was corrupt. I removed the file, created a new one, and applied user:mail permissions. I then created a new email account, then copied the user’s encrypted password after making entries in shadow for the existing users. I was then able to login to each webmail account without issue.
