This user is having a very unusual problem. Notify reports that a mail arrives. After that, mail does not show on mailbox, but if he runs a search ( CTRL+F )the mail exists and he can open it.
He can view all incoming mail on webmail, but not in the GW client.
GW 8 SP 1 release 88138.

User has caching mailbox setup, tried "on line" mailbox and it is the same.
Mailbox is not filtered in any way.

A little help over here please ..
Thank you in advance