Rated 3 out of 5 stars

I got this extension to do regex searches. Which it does... except for stuff like fr:!workdomain.com

I've tried multiple gyrations, and I can NOT get it to display everything that *didn't* come from *.workdomain.com (eg all outside emails). This is annoying.

It apparently uses the javascript regex engine, which doesn't have any documented "not" searches, except for x(!?y), which doesn't work for this (I tried it).

So the regex implementation is inadequate.

This review is for a previous version of the add-on (1.2). 

Yes, Tokens like ['simple', 'regex', 'headerre', 'bodyre', 'fromre', 'tore'] should be the last one and has no "NOT" searches.

But if you only need to filter out email from internal, a normal "from" filter is enough:
f:-workdomain.com

If you really want to use regex, you can try:
fr:/@(?!workdomain\.com)/i

Thanks.