Mails that have been sent to you in error can be forwarded in Thunderbird to the correct recipient of the email. This is happening regularly in companies for example. The forwarded message however does not look like the original one because it normally has the mail header attached to it. This looks pretty ugly and is not needed most of the times.
The Thunderbird add-on Mail Redirect allows mail redirects instead of forwards to other recipients. This ensures that the recipient will only see the original message and not the information that are attached when the email gets forwarded.
The extension Mail Redirect adds a Redirect option to the Thunderbird right-click menu which means that more than one email can be redirected at a time. Alternatively the keyboard shortcut CTRL + B can be used to redirect messages.

Thunderbird Archiving Shortcuts
Mails sent with BCC did not reach recipients ?
Thunderbird Email Address Auto Cleaner
Increase Thundebird’s Mass Mailing Capabilities
Copy Tables In Thunderbird
This is the kind of stuff that I’d sometimes like to have, but don’t want to install* an extension for.
Also, it’s pretty basic functionality, so it should be part of the TB core IMHO…
* if only there were bookmarklets for Thunderbird…