Review for Mail Redirect by Andrew Nguyen
Rated 5 out of 5 stars
Works exactly as advertised!
One caveat: the download on mozilla.org (https://addons.mozilla.org/en-US/thunderbird/downloads/latest/550/addon-550-latest.xpi?src=addondetail) downloaded mail_redirect-0.7.4-mz+tb, which does not work with TB 3.1.1.
I downloaded the .xpi from the URL in one of the reviews (http://downloads.mozdev.org/mailredirect/mailredirect-0.7.4-tb3-20100708.xpi) and that installed and worked OK w/ TB 3.1.1.
To create your own collections, you must have a Mozilla Add-ons account.