Well, let's see. If 30,000 members really started saving 100 PMs a piece, then the usage would be tremendous. Of course, there's not going to be that many saving messages.
There is now an easy way to purge your messages. There is a check box on the top of the list that will let you check them all and then select delete at the bottom. There is also a link at the top to empty the box.
If you want to save them, you can save them to your own computer by the links at the bottom of the PM page.
For now, 100 will remain the limit for registered members. However, that number will increase with promotions which we'll be using in the future. For example, a member that reaches 1000 posts may get an increase of 50, a contributor may have double that amount, and so on.
The auto-purge is a nice means of getting rid of stuff, but it sure perturbs people when something they were saving is deleted.
Thanks for the suggeston.