Rated 5 out of 5 stars

Perfect, very useful ! You can also make a regex to display only the real IMAP received timestamp.
However, didn't find a way to capture both the timestamp and the sender host alongside nicely.

EDIT: (answer to the dev) Please yes if possible. Multiple capturing groups would be a great and powerful feature!
I know About the IMAP Received add-on and did the Config Editor trick, but your add-on is much better.
Thank you for your fast reply and for this great add-on!

This review is for a previous version of the add-on (2.1.1). 

I can add support for multiple capturing groups. Please, let me know if you need it.

BTW, you can have real received timestamps in a column with IMAP Received Date add-on. The add-on doesn't support Thunderbird 78 yet, but suggested workaround works: https://blog.kamens.us/send-later.