Rated 3 out of 5 stars

Sadly there is no way to respond an answer ... so next entry.
"resent" email *I have to select an email SENDER address* ...
So why it uses the original sender address ????
The original "resend" addon wasn't doing this... only the other "bouncer" addon...
And yes... EVERY GOOD MAIL PROVIDER has to check sender address and block emails outside his domain / not registered by AUTHORIZED account.

EDIT:
Then the (german) description is wrong which Firefox always redirects me to...
There is written: ~ "different behavior of 'umleiten' which is like a forwarding without citate" which wasn't the case so far I remember.
But this is a redirect (and not a bounce which you mean with your plugin behavior) .
And maybe you are only not aware about the difference between envelope sender and From: address...

BTW there was a One-by-One Forward plugin which is also not available anymore but for all which wants a "mass forward/REDIRECT) there is "ThunderFWD" -ä not so nice interface but working as wanted...

This review is for a previous version of the add-on (1.33). 

> So why it uses the original sender address ????
Because that's the purpose of this add-on! Please read the note on the add-ons homepage https://www.ggbs.de/extensions/SimpleMailRedirection.html

Please also note that there is a difference between Thunderbirds resend function and this add-on which unfortunately also uses the term 'resend' (but i used the term earlier!)

Rated 2 out of 5 stars

Sadly I run with latest Thunderbird / just installed addon into same problem as b4c89e: " Transaction failed Unauthorized sender address."
It seems that your addon let decide which email should be used to sent the "redireted" email but send the email with origin email addres... this was working withe the original mail redirct addon

This review is for a previous version of the add-on (1.33). 

"Unauthorized sender address" and similar errors are not a problem of the add-on, it's a problem of the provider you are using to resent the mail. They simply does not allow a sender address which is not from their own domain.
The only workaround is to use another mailprovider which allows arbitrary sender addresses.