I use an IMAP account provided by the CMU ECE Dept. for my primary email. I have a number of folders into which I file various emails, and I have Sieve enabled to automatically sort email into appropriate folders as it arrives. With Thunderbird’s default configuration, this is a bit of a problem, because it only checks Inbox for new messages, and not, e.g., Inbox.class. Thus, I have to manually select Inbox.class to determine whether any new mail is available. I found a way to have Thunderbird automatically check these subfolders, and the purpose of this post is to share that.
From the Thunderbird support website, have a look at Check all IMAP folders for new mail. It did the trick for both my Mac OS X, Debian Linux, and Windows XP Thunderbird installations.
To summarize, you need to add the following line to user.js:
On my Mac, this is in ~/Library/Thunderbird/Profiles/1234abcd.default