Alles was so fehlt... insbesonders wenn man Google Mail, Contacts und Calendar benützt.
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
German Dictionary (new Orthography) for spellchecking in Mozilla products
Allows bidirectional access to Google Calendar
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Access to Google contacts and synchronize them with Thunderbird address books.
This extension allows you to manually sort (order) your folders in the folder pane of Thunderbird or automatically sort them, but in a better way. This extension also allows you to re-order accounts in the folder pane.
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
The "Swiss army knife" of folders. Turn your favorites into tabs - open folders and subfolders, move mails without scrolling around or searching. powerful + easy.
See new mail at a glance after automatic filtering - supports quickFilters addon!
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
Thunderbird Message Filter Import/Export is a thunderbird/mozilla extension to import/export message filters.
It adds a button that can be put in toolbars and that open the addressbook in a new tab