Forward Icon in Inbox

One of my users returned from vacation to find that every mail he recieve has the forward icon infront of it in the Inbox. Has anyone any idea why this could be?

Subject: Forward Icon in Inbox

This may sound obvious but…check that he didn’t have a mail rule forwarding his mail to someone else automatically.

or that someone doesn’t have delegated access to mailfile and was fwding to themselves or something

Subject: RE: Forward Icon in Inbox

There is no mail rules, I’ve checked. The icons appears in the same column as icons that I can trigger when sending a mail to someone that is urgent (exclamation mark icon)etc, not in the column where the forward icon appear when forwarding mail.