Rated 3 out of 5 stars

0.15.2 works, but
testing the settings triggers an error:
[XX] error at undefined:224: [Exception... "Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getBoolPref]" nsresult: "0x8000ffff (NS_ERROR_UNEXPECTED)" location: "JS frame :: chrome://mailboxalert/content/mailboxalert_funcs.js :: <TOP_LEVEL> :: line 224" data: no]
Linux, TB 7.0.1

This review is for a previous version of the add-on (0.15.2).