Check Attachment before Send Requires Restart
Confirms to send a mail with any attachment.
Single Domain Requires Restart
Warns if you send mail from or to a specified domain. If there are multiple accounts in your profile, you can isolate one so that you can't send mail to that domain from outside or vis versa without warning.
RM: EXTERNAL: Requires Restart
Removes 'EXTERNAL: ' from the start of an email subject if it is preceded by 'RE:' or 'FWD:' (case insensitive). The removal is done after the 'Send' button is pressed.
Edit Message Encoding Fallback Requires Restart
Fallback to a safe encoding, if you are replying to a message with unsupported encoding like UTF-16LE. (workaround for the Bug 961983)
mms Auto Correct Requires Restart
AutoCorrect for the Compose window.
Attachemnt Encoding Detector Requires Restart
To detect file encoding of attachments, this forces to Thunderbird to use an encoding detector for a specific locale instead of the generic one.
Sensitivity Header + SPX Requires Restart
Implement the "Sensitivity" header for outgoing messages (described in RFC 4021 section 2.1.55).
Forked from another add-on developed by ff_bob, added SPX header for Sophos security appliances
Copy Message ID Requires Restart
Adds a button to the message view toolbar to copy the message ID to the clipboard. This is useful when sending email replies via the command line.
Insert Link from Local File Requires Restart
Inserts links from local files via drag and drop on the composition window.
Colored Recipient Type Requires Restart
Customize background-color of the recipient address fields for each recipient types of To:, Cc:, Bcc:.Customize background-color of the recipient address fields for each recipient types of To:, Cc:, Bcc:.
One-by-One Forward Requires Restart
Highlight multiple emails, right-click, then select "One-by-One Forward". This extension will allow you to forward the selected emails, one-by-one, to the recipients you specify using your choice of attachment handling.
Help in reminding mails to be answer or sent again. Choose a reminder date for each received or send message that are highlighted in the message list, depending on their status (expired, soon to exprire, to be reminded). Sending a reminder is eased.
Smart Quotes Requires Restart
Enables “Smart” Quotes for Thunderbird Email
PennyPost Requires Restart
This extension makes it very easy to generate and attach stamps to outgoing mail. It also automatically detects and verifies stamps on incoming emails. The MBound algorithm requires a 16MB fixed table to work, HashCash is more CPU intense.
Path Linker Requires Restart
Add menu commands for replying to multiple messages at the same time.
Posting Style Enforcer Requires Restart
Automatically converts top-posted messages to use bottom-positng or vice versa. Interleaved posts are left alone. Detects automatically added text and supports a per-contact list of exceptions.
Tategaki Requires Restart
Tategaki allows vertical writing-mode on mail compose window.
Stop Ignoring Reply:To Requires Restart
Default "Reply" functionality pays attention to "Reply-To" in original email
FastCC Requires Restart
A Thunderbird extension that let you switch to cc: with the ALT+CTRL+C keyboard shortcut!