When I ask Windows Backup to "backup once", the backup is successful; however, when I schedule a daily backup, nothing happens, and the event log only shows Kerberos Authentication errors. Consistently, on the second that the scheduled backup is
supposed to happen, there is a 0x18 KDC_ERR_PREAUTH_FAILED.
From my understanding, Kerberos preauthentication is important for security, and thus not something that should be disabled for users or administrators.
I've reentered the windows credential for the administrator to access the file server from the mail server; however this doesn't seem to help.