We recently added the Debian Icedove mail client to the [libre] repo (actually "icedove-libre"), and encourage Thunderbird users to switch. For a long time our one of available mail clients was Thunderbird-libre (a version with free addons and free searchplugins) but the specific problem is that it disallows selling unmodified copies and requires rebranding modified versions.
Icedove is an e-mail client distributed by the Debian project. It is based on Mozilla Thunderbird. With Icedove, the Debian project aims to provide a version of the Mozilla Thunderbird e-mail client which has not yet been kept in synchronization with upstream development of Thunderbird as originally planned. It removes the proprietary artwork and plug-in repositories used in the official release by the Mozilla Corporation, but this program has a freedom issue: recommends non-free addons and non-free searchplugins.
So, Márcio Silva (coadde) and André Silva (emulatorman) began creating a libre version of Icedove without non-free addons and non-free searchplugins including the advantage provided by Icedove, so that Parabola could continue to distribute the software with modifications permitted, without being bound by the use of trademark requirements that the Mozilla Foundation had invoked.
Since today, Parabola GNU/Linux-libre has Icedove-Libre with Language Packs included on [libre] repo.
Enjoy the Freedom!