Being Ubuntu’s standard email client, Mozilla Thunderbird is also available for Windows and OS-X. Similar to the Firebox browser, the functionality of the program may be extended by a multitude of add-ons. Since version 60, released in summer 2018, Thunderbird has been using a new extension interface called MailExtensions, which breaks the compatibility of all old-fashioned extensions programmed in XUL, that will be removed step by step. This rases serious upgrade problems for long-time Thunderbird users. According to the tb-planning group, all “legacy” add-ons will be completely deactivated in 2020, when Thunderbird 78 is published.

With version 60 and 68 Thunderbird offered numerous usability improvements and a renovated design including a flat logo. The calendar, which previously had to be installed separately using the Lightning add-on, is now an integral part of the program. To synchronize calendars and addressbooks over the network, the CalDav and CardDav protocolls are not build in out of the box, but support may be added thanks to a separate add-on named TbSync, which has a provider for Exchange Active Sync, too. For those who cannot live without Google Calendar, there is an add-on as well. The previously recommended Sogo connector no longer works. The Add-On CardBook is a solid choice that supports the standards CardDAV and VCard, however it installs itself as an additional address book.

While e-mail encryption has always been complicated for average users, for many years the EnigMail extension offered a proven way to secure a mail’s content in Thunderbird with PGP. Since EnigMail’s developer would not port it to the new Extension API, the Thunderbird developers plan to support encryption with OpenPGP out of the box starting with Thunderbird 78, expected in summer 2020. There is a sad footnote however: in 2018 security deficiencies (keyword: Efail) discovered in PGP caused a security nightmare, for which neither the developers of Enigmail nor Thunderbird are to blame. Switching to S/MIME as an encryption alternative is useless, as there are even more security gaps in this standard.

Storage und Backup

All mails, adress books and account settings as well as most add-ons may be conveniently archived by copying the profile folder located at $HOME/.thunderbird.

Installation

For all supported Ubuntu versions, security updates to Thunderbird 60 are delivered. However, the upgrade to Thunderbird 68, published in August 2019, was postponed until the release date of Ubuntu 19.10 im Oktober 2019. Everybody who wants to use the upgraded version before, can download it from Thunderbird’s official website and install it in parallel. However, because of the API changes it is possible that legacy add-ons will no longer work.

To install Thunderbird from the official Ubuntu repos, just type:

sudo apt install thunderbird

Alternativen

Geary ist a slim e-mail-client for the Gnome Shell; at Elementary OS it is known under the name Pantheon Mail. Gnome ships Evolution, an alternative to Microsoft’s Outlook, which integrates e-mail, contacts, calender, tasks and notes. KDE has a PIM (personal information manager) of its own called Kontact, which uses Kmail for e-mail.