The popup window as of Firefox 58 does not have scroll bars, which makes this unusable. Might as well use bookmarks.

worked for awhile, but i would say just over this past week it has just stopped with any notifications at all. don't know if an update got pushed out that broke this.

The popup is very helpful, however in Firefox 57 i have no scroll bars in the pop up making reading an email impossible. If it is going to use popup window it needs scrolling otherwise just open a new tab.