Review for Mailbox Alert by John
Rated 5 out of 5 stars
I just installed this, so I don't have much of a review yet. But for those who want the alert to stay until clicked, try using a popup duration of 86400 seconds. That's 24 hours. Go higher if you need longer than that. A week would be 604800 seconds.
This review is for a previous version of the add-on (0.14.6).To create your own collections, you must have a Mozilla Add-ons account.