Version: 1.7.2 (using KDE 3.3.2, compiled sources) Compiler: gcc version 3.4.2 [FreeBSD] 20040728 OS: FreeBSD (i386) release 5.3-STABLE In a bout of frustration with KMail, I switched to Mozilla, which promptly created "Trash" sub-folder of my INBOX on our Cyrus IMAP-server (I configured KMail to use a local trash-box). There is currently one e-mail message in this Mozilla-created Trash subfolder. To delete a subfolder, means opening it first. KMail can not, to save a life, open a single message in it -- the progress bar just keeps going sideways. When I tell it to just delete the folder, it is immediately removed from the tree by KMail, but the program will either crash or complain about being unable to "retrieve the structure of a message". Needless to say, the subfolder is not, actually, removed and reappears, when KMail restarts.
I was unable to reproduce this using Courier IMAP, kmail 1.10.1, and thunderbird 2.0.0.14. While I do get an error when trying to delete the Trash folder in INBOX, this is because it is not allowed by my IMAP server (nor is it even an option on the majority of mail clients). However, any messages placed in INBOX/.Trash by Thunderbird are viewable and deletable by Kmail. Also I should note that my IMAP server creates the default layout with the Trash folder in INBOX. I also created a folder named mozilla in the INBOX with Thunderbird and moved some messages to it. These were are viewable with kmail as well, and I was able to delete the folder without errors. Perhaps this needs to be tested further by someone with a Cyrus IMAP server.