mailwatch-plugin only works when Thunderbird is running

[Jon]

Hello!

I have got a little problem with the mailwatch-plugin 1.1.0 on Xubuntu 10.04: 
It only works while Thunderbird is running, which somewhat contradicts it's 
purpose. ;)

I am using an IMAP mailbox with SSL/TLS over the default port (993). I should 
also mention that mailwatch used to work well on Xubuntu 8.04 with the same 
settings.

Mailwatch's log is completely empty. Where can I look for the source of the 
error? Thank you very much in advance for all hints and suggestions.

Best wishes

Jon