Flexible Identity Requires Restart
Selects an identity based on the recipients list when sending an email
GNOMErunner/GTK for Seamonkey 2.x Requires Restart
GNOMErunner/GTK - a classic unix theme for Seamonkey 2 (aka suiterunner)
using the GTK+ stock items and icons from the gnome iconset, resulting in a more consistent desktop integration on Unix.
EzStylist Requires Restart
Allows including CSS when composing e-mails.
Caret Out Requires Restart
Disables change of the caret browse mode by shortcut key(F7).
Remembers last selected (hilited) extension/theme/plugin/userstyle in Add-ons Manager. Version 3.0 also includes sorting buttons. Turn off/on the add-on selection list box and/or fine tune behavior via its Options.
Highlighter Requires Restart
Quickly highlight some text in Thunderbird message composing windows.
MDN Interface Documentation Generator Requires Restart
Generate MDN Interface Documentation from IDL files.
Send Later Requires Restart
True "Send Later" functionality to schedule the time for sending an email.
1-click Online Document View Requires Restart
Open DOC, DOCX, PDF, PPT, PPTX and TIFF files linked in any webpage directly with Google Docs viewer using "1-click Online Document View", with a single left-click of your mouse / trackpad!!
Thunderbird Integration for JIRA Requires Restart
This is a plugin for Thunderbird 3.3+ which is able to create Atlassian Jira issues out of e-mails or add the content of an e-mail as a comment on an Jira issue.
Contact Photos Requires Restart
Displays contact photos in the message header.
Peachphone : virtual phone (Android/iPhone) Requires Restart
Send SMS and MMS worldwide, Video from your webcam, video from Youtube, send photos, manage your contacts (Thunderbird, Outlook, MSN, Yahoo)
Year view Requires Restart
Year view for calendar.
Mailopen Requires Restart
Open an email file from the commandline
ToggleReplied Requires Restart
Enables toggling of Replied/Forwarded states of messages.
FiltaQuilla Requires Restart
Adds many new mail filter actions - launch a file, suppress notification, remove star or tag, mark replied or unread, copy as "read", append text to subject.
ToneQuilla Requires Restart
Adds a new action to mail filters to allow playing a particular sound when the filter matches. Also includes several sample sound files.
gContactSync Requires Restart
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.
Clean Subject Requires Restart
"Clean Subject" cleans the subject from multiple occurrences of subject prefixes such as ("Re: Re-2: Re:") and postfixes that are inserted by other clients. Words like "[SPAM]" can be cleaned as well. These prefixes can be defined in the preferences.