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Provider for Google Calendar

Allows bidirectional access to Google Calendar

Rated 3 out of 5 stars (1,650)
186,480 users

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British English Dictionary (Marco Pinto)

A fork of Mark Tyndall's add-on, based on David Bartlett's
British Dictionary R1.19 for Firefox, Thunderbird and SeaMonkey.

V3.3.3 has 140 000+ new words and also fixes.

Rated 5 out of 5 stars (83)
165,407 users

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English United States Dictionary

English United States (en-US) Dictionary as shipped with Thunderbird 115 ESR and Firefox 115 ESR.

Rated 4 out of 5 stars (39)
68,459 users

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Deutsches Wörterbuch

Deutsches Wörterbuch (neue Rechtschreibung) für die Rechtschreibprüfung in Mozilla-Produkten

Rated 4 out of 5 stars (82)
229,423 users

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Diccionario de Español/España

Diccionario de Español/España

Rated 4 out of 5 stars (167)
59,865 users

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CardBook Featured

A new Thunderbird address book based on the CardDAV and vCard standards.

Twitter: @CardBookAddon

Rated 4 out of 5 stars (445)
66,783 users

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Mail Merge

Create and Save or Send Multiple Individual and Personalized Messages from a Draft

Rated 5 out of 5 stars (226)
64,695 users

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DKIM Verifier Featured

Verifies the DKIM-Signature of an e-mail.

Rated 4 out of 5 stars (45)
17,695 users

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Dizionario italiano

Add support for Italian to spellchecking

Rated 4 out of 5 stars (71)
73,164 users

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Send Later

True "Send Later" functionality to schedule the time for sending an email.

Rated 5 out of 5 stars (263)
99,536 users

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Woordenboek Nederlands

Woordenboek Nederlands met de woordenlijst van OpenTaal.

Rated 3 out of 5 stars (70)
22,929 users

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Signature Switch

Switch the signature on/off or choose a new one from your predefined set.

Rated 4 out of 5 stars (272)
49,633 users

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Lightning Calendar Tabs

Zobrazí záložky, pomocí kterých je možné rychle přepínat aktuální období v kalendáři Lightning. Všechny pohledy kalendáře jsou podporovány. Je možné upravit barvu textů záložek.

Rated 4 out of 5 stars (24)
28,109 users

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Diccionario español Argentina

Diccionario ortográfico de español de Argentina.

Rated 4 out of 5 stars (93)
12,589 users

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QuickFolders (Tabbed Folders)

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!

Rated 5 out of 5 stars (187)
14,674 users

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Український словник

Український словник перевірки орфографії

Rated 5 out of 5 stars (57)
10,825 users

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Diccionari català (general)

Diccionari ortogràfic lliure català (versió general).

Rated 4 out of 5 stars (40)
12,412 users

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Canadian English Dictionary

For some reason, Mozilla doesn't have a Canadian localization team, but I know that even the British dictionary doesn't quite cut it for the truly patriotic.

Rated 4 out of 5 stars (82)
9,296 users

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Emoji

Add emojis to your e-mails.

Rated 4 out of 5 stars (64)
24,124 users

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Addressbooks Synchronizer

Synchronizes selected addressbooks with other instances of thunderbird
using local files, webdav servers or imap servers

Rated 4 out of 5 stars (79)
23,943 users

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