Out of Office -- Send on Behalf of

When a user’s assistant sends an e-mail to the company on behalf of the user, half of the out of office replies go to the user and half go to the assistant. This has been noticed since an upgrade of client and server from 6.5.4 to 8.0.1.

Has anyone else seen this? Any suggestions?

I don’t want to “test” too often since this occurs when hundreds of people are e-mailed.