Rated 5 out of 5 stars

yes
i changed background color:))
before instal i opened xpi file with win rar then opened with win rar chrome/mailboxalert.jar and editet content/mailboxalert/newmailalert.css
now this extesion is 5 star:))

This review is for a previous version of the add-on (0.16.1). 

Rated 4 out of 5 stars

can i change default colors?

This review is for a previous version of the add-on (0.16.1).