All SQL Server services starts by the domain account.
After I created maintenance jobs, all jobs failed with the message:
"The job failed. Unable to determine if the owner (DOMAIN\SQLPROD) of job Transaction Log Backup Job for DB Maintenance Plan 'UserDB' has server access (reason: Could not obtain information about Windows NT group/user 'DOMAIN\SQLPROD'. [SQLSTATE 42000] (Error 8198)).
In the same time jobs run fine as 'sa'. Output message:
"Executed as user: 'DOMAIN\SQLPROD'....
...The step succeeded."