we use GroupWise 8 HP2 (Server & Client) on NetWare 6.5SP7 and gweml to open eml-files.

Now we have the following problem on only 1 Mailbox:

If I open eml-files I get an error D107 or an empty Mail appears or an old email from 2003 opens but not the really opened eml-Mail.

This Problem only occurs on one Mailbox - in all other Mailboxes it works fine.
If I use another mailbox with proxy rights to this mailbox there's also no problem.
GWCheck - changes nothing.

What could I do to fix the problem of this mailbox?