SQL logs showing login that I can't find Within my SQL server logs, I am showing a successful login to a database from an account (SERVER\loginname) that I cannot find in either Security &gt; Logins OR Database &gt; Security &gt; Users. This login is being used by a program to execute a task (which it does successfully), so it's not a security compromise, but I cannot for the life of me figure out where it is and I need to find it to make an adjustment. 

A couple more notes: I do remember adding this specific login a while back and there was something special about how I had to do it because it is not a domain account. Instead, it uses pass through authentication (same local account name on the app and SQL server with the same password). I cannot use it to login via SSMS. It is not a part of a group membership. It is not showing when I do a SELECT from the master syslogins table.

Does anyone have any ideas for my brain-fart?
Can you try running the following:

EXEC xp_logininfo @acctname = 'SERVER\loginname', @option='all';


This should return the SQL login the Windows user is being authenticated as.

Reference here.