I have been working on the private message system for a bit to bring it up to the level you are accustomed to from other trackers.

This includes:

A proper "sentbox" where you can view all your sent messages
Conversations, no more wall-of-text quotes in every message necessary
Ability to sticky conversations (independent of highlighting, which is still possible)

In addition, I separated the system messages from private messages so your inbox is no longer clogged up by dozens of "you have been quoted in the forum"-messages or suchlike.

System messages can still be deleted one by one, but regular private messages cannot. You can delete the whole conversation instead. Your conversation partner can of course still view the conversation even after you have deleted it. If you delete a system message conversation and you get a similar system message afterwards, any non-deleted messages within that conversation will be restored.

All old messages were moved over to the new system and were also assigned to conversations based on participants and subjects. Some early messages did not have subjects (for whatever reason) so they were either assigned one from the first words of the message or got a generic "-- NO SUBJECT --" subject. You can view the old messages at inbox_old.php (will be removed in a few months).

If there are any discrepancies between the new and old messages/conversations, or if you find any bugs, please do not hesitate to send a staff PM.