Does this exist by default, or any hacks for it?

[cheat-master30]

Someone on my own forum PMed asking this semi unusual question:

You know where you can create custom folders for PMs, can you set it so that, say, PMs from a certain member are automatically put in one of those folders? Or PMs with a certain subject, title etc?

This made me look for such a feature, and it does not seem to be with the other PM options, so does it exist by default, and if not, is their a vBulletin 3.6.7 Patch Level 1 compatible modification to achieve this?