Hide message pane and then show message pane. If the message list isn't long enough to need a scrollbar when the message pane is hidden, it won't be there when the message pane is shown again.

I see it: Message Body pane does not have scrollbar as needed after hide/show Message Envelop part by using a small '+' on the left. (I use little bit dif. wording).

Samuel Solon: your problem description was fairly minimal, and you didn't include a build ID. I am guessing you were hiding the message pane either by the View | Show/Hide | Message Pane menu item, or perhaps by clicking on the dragspot in the splitter bar. I am seeing the scrollbar redisplay in the message list as expected when the message pane is hidden, then redisplayed, using either technique, in 1.3 Final and a recent 1.4b nightly. Please confirm this. Olga: I think the symptom you described in comment 1 is different from Samuel's. However, I tried that too: I used the "twisty" (or [-/+] box) to contract headers, which made the scrollbar in the message pane disappear; but on re-expanding headers, the message pane's scrollbar was redisplayed as well.

=>WFM as per comment 2