I was trying to write a script which would add a new mail icon to my system tray, but apparently Thunderbird does not support checking for new mail from the command line.
I've tried a number of plugin, but they all seem to have only a vague description. The ones I tried just modified the new mail popup.
Therefore I'm looking for a plugin which displays an icon in the system tray for unread mails. It's not necessary to display the number of unread mails, but it would be nice though.