[MAPI_E_FAILONPROVIDER error while trying to logon other user's mailbox

[inmar]

Hello,

My task is to open other user's mailbox, create subfolder and restore
messages.

I have a user with full mailbox access permission. steps followed to achieve,
1. Opened a session with that user.
2. Open address book (GAL).
3. Select target mailboxes to restore.
4. export eml file to target's folder.

Exporting to user who is part of same exchange server as the user having
privileges is working fine.
But exporting to a user who is part of other exchange server within the same
domain gives MAPI_E_FAILONPROVIDER error

Is this possible ? do I need to provide any other permissions to that user to
access other exchange server's mailboxes ?

Thanks
Inmar