Hello Sam,

Some of my users are surprised and astonished that the webmail sometimes puts their messages into "wrong" Sent subfolder.

It's because they use IMAP client mostly and webmail only occasionally and because the autorenamesent feature works very simple currently. When you create Sent subfolder for previous month you don't care about what real date of sending messages is.

I think that autorenamesent feature can be a bit more intelligent. I propose to grab the date from timestamp included in name of files and create missing Sent subfolders if it's necessary.