The correct error number es 2273.
The problem is here: http://technet.microsoft.com/en-us/library/bb490707.as=
It says when you login your username is added to "net name" alias list for =
messaging, but I have many users that login to domain controller but her us=
ername isn=B4t added to "net name" alias list. Then, they cant receive mess=
ages and sender gets the error.