Add-ons

Remove Duplicate Messages by Eyal Rozenberg

Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).

Mail Redirect by Onno Ekker, Pawel Krzesniak

Allow to redirect (a.k.a. "remail") mail messages to other recipients.

Collector's Note なるべく余計な手を加えずにそのまま転送するために。

CompactHeader by jmozmoz

Add symbol in header plane to switch between compact and expanded view. Work only for Thunderbird 68.0 and older. Currently, there are no plans to update this for newer versions.

Quote Colors by Malte Ruecker

Quote Colors allows you to select text and background colors of different quote levels which are applied when reading or printing mail/news messages. Additionally, you can choose between graphical and traditional plain text quoting display mode.

Collector's Note 標準のスタイルよりこっちの方が自分は見やすい。

Thunderbird Message Filter Import/Export Enhanced by kounavi

Thunderbird Message Filter Import/Export Enhanced is a compatibility port of Wind Li's add on.
Original add on here: https://addons.mozilla.org/en-US/thunderbird/addon/thunderbird-message-filter-imp/

Thunderbird Message Filter Import/Export by Wind Li

Thunderbird Message Filter Import/Export is a thunderbird/mozilla extension to import/export message filters.

Collector's Note 常用は言い過ぎかも。1回使ったらもう使わない類のアドオンだし……

Correct Identity by ldreier, Dennis Verspuij

Ever sent mail from the wrong email address because you forgot to select the correct identity?

Collector's Note プライベートなメールと仕事のメールとを同じ所にぶち込んでるので、差出人を選択し忘れるのを防ぐために。

Folderpane Tools by chuonthis, Philip Chee

Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.

Collector's Note 常用は言い過ぎかも。1回使ったらもう使わない類のアドオンだし……

Priority Switcher by H.Ogi

Change priority of the received messages from the toolbar button and the context menus...

Before Tabs Toolbar by Paenglab

Adds a toolbar before the tabs.

Ruler Bar by Piro (piro_or)

This appends a ruler to the mail composition window.

Collector's Note なんとなく、あると安心する。無くても使える。そんな機能。

XUL/Migemo by Piro (piro_or)

This provides dictionary-assisted search (Migemo search) and regular expression powered search for "find in this page" and other features.

Collector's Note 対応させてみたので入れてるけど、いまいち自分でも使ってない。

CuteMenus - Crystal SVG by mrtech, Static_Nexus, others

Note from Mozilla: This add-on has been discontinued. Try Menu Icons Plus instead.

Adds icons to all menus along with some other features...

Collector's Note メニューの視認性が上がる。

Sync On Arrival by Michael Buschbeck

Downloads new message headers (and bodies, if configured) immediately when Thunderbird detects new messages in an IMAP folder - that's more or less what the "download_on_biff" preference promises to do, but somehow fails to deliver...

Collector's Note IMAP使うならこれがないとやってらんないと思う。