Wurdearring: 2 fan de 5 stjerren

I crave for this addon to work but I get a strange error when trying to use it. Whenever I open a mail I get a popup with the header "[Javascript Application]" and window body being:
closing socket2

1 NO Empty username or password. **************** "

The **** are actually a random string of lower case letters and numbers with that length.

Dizze beoardieling giet oer in eardere ferzje fan de add-on (0.5.1).