Default UserPrincipalName at Logon

Hello,

i've set up an active directory based on windows server 2003. in this

environment

it is not possible that the UPN and the SAM-accountname is the same.

So at

logon the users habe to type in their full UPN (<first

name>.<surname>@mydomain.com).

Is it possible to tell the winlogon process to use a default upn-

suffix at logon so

the users have only to type in their name withouth suffix like it is

with the SAM-accountname??

Greetz

Stefan