There are sporadic reports of a crash upon opening the mailbox for the first time.

I've narrowed it down a lot. Here are the key components:

1. This is a WoW engine crash. Thus, it is a WoW bug.
2. It is triggered by addons. In particular, BeanCounter (from Auctioneer) and Prat (a chat addon).
3. It affects only WINE and Mac users... Which means it's an OpenGL bug.
4. It applies only the first time you open a given box full of mail. Meaning, if you restart the game, log in on the same character, and check your mail again, it won't happen.
5. I have a system which exhibits this bug. On the SAME system, with an SSD instead of a regular hard drive, the bug did not occur.

4+5 together suggest very strongly that this is a speed-of-loading race condition of some sort; if the requested data are either on an SSD (thus accessed extremely quickly) or in the disk cache (thus accessed extremely quickly), nothing happens.

I don't have a suggestion as to a reproducer without those addons, but I would guess that if you have a triggerable race condition with some kind of asset loading in the OpenGL code, which affects both WINE and Mac users, it is probably possible to find it other under circumstances -- making the existence of a completely reliable reproducer an utter win, no?

This has been around for a long time, probably since 3.0. If you search on likely terms ("crash opening mail wow", possibly plus beancounter or prat), you should find tons of reports.

Reproduced with current versions of Prat and BeanCounter. Have been seeing it since WINE 1.0, currently on 1.0.29, and have also seen it on Mac.

Can you post the error log into this thread please? It should be located in an "Errors" folder in your World of Warcraft directory.