How EV client V9 retrieve credential information?

Hello all,

We get an issue with one of our VIP user.

She gets request for credential when she try to access any archived email in her EV environment (connected to the network), and in fact the credential logon field were with email address, it should have been with "domain\logon"

As soon as we have corect the logon information, no more pront for password.

Is it a know issue on EV side?

How EV 9 and EV 10 client is getting logon information? Via Credential Manager of Windows 7?

Full workstation issue?

We only had one or two users with this issue, so I guess that it is not a server issue.

Thanks a lot for your help !

Regards