From MozillaZine Knowledge Base

A lot of changes in backend code and features have been performed since the release of Thunderbird 2.0 in April 2007, and Thunderbird 3.0 is entering the beta phase with an expected final release in early (Q1) 2009. This article describes noticable changes from the user's perspective, thus won't address all the technical details and bug fixes which were done behind the user interface. However, for those interested, links to relevant bug reports, wikipages, or forum threads are provided.

Many but not all of these items also apply to SeaMonkey 2.0.

Notes:

1. Unless explicitly stated, the contents of this article apply to all major platforms (Windows, Max OSX, Linux).
2. All descriptions refer to the default theme, thus items may be missing or appear differently if you use another theme.
3. Many themes and extensions will not work (yet), thus verify that they have been updated for Thunderbird 3.0.
4. Any userChrome.css entries you have defined for Thunderbird 2.0 may no longer work with the new version.

Message Viewer

The most obvious change becomes apparent when opening a message in Thunderbird 3.0, there has been a substantial redesign of the header pane of a message [1], and tabs were introduced to allow easier browsing of multiple messages or folders within the same window [2]. These new features are functional but not yet finalized.

Action Buttons in Header Pane

• The upper right corner of the opened (non-brief) header pane has buttons for frequently used actions added, which replicate the functions of the icons in the main toolbar.
• There has been some extensive discussion on the usefulness of these redundant buttons [3], thus it is envisioned to make the new items configurable similar to the toolbars [4].
• For the time being, you can include the following code into your userChrome.css to suppress these items:

#expandedButtonBox, #hideDetailsBox {
    display: none !important;
}

• Individual buttons can be addressed with .hdrReplyButton, .hdrForwardButton, .hdrJunkButton, or .hdrTrashButton.

Address-Book Status for each Address

• There is a star next to each shown e-mail, which is blank if the address is not yet present in the address book, and filled in yellow if it was found [5].
• Similar to the bookmarking function in Firefox 3.0, click on it to add or modify an address-book entry for this address.

Message and Folder Tabs

• Messages and folders can be opened in separate tabs now.
• Note that after the redesign, the extended folder columns are no longer available. An extension is provided to add those back [6].
• Right-click on a folder or a message in the thread pane and select "Open in New Tab" from the context menu.
• It is not possible to open messages in a tab by double-clicking, it will open in a separate message window [7].
• The tab bar is also visible when just a single tab is present [8]. As a workaround, it can be hidden using the .tabmail-tabs class, but be advised that you won't be able to "get back" when navigating into a dead end.

Large Images

• Images which are larger than the width of the window can now be automatically resized to fit the window width [9].
• Watch for the zoom icon to show up in oversized windows, and click into the image to toggle between "fit to width" and "original size".
• Alternatively set mail.enable_automatic_image_resizing (defaults to true).

Remote Content

• Thunderbird 3.0 comes with a disk cache, which can cache any remote content [10].
• These are usually images referred to in HTML messages, or something trivial as the startup page, but also certificate data and even update files are cached.
• This setting is in the Advanced pane. To disable the cache, set its size to 0MB or browser.cache.disk.enable to false.
• Note that messages themselves are not cached. IMAP messages may be cached in the future [11].
• While "about:cache" has been implemented, there is no easy access to the contents of the disk cache [12]. As a workaround, define the start page in Advanced → General as about:cache?device=disk, which allows you to examine the contents whenever the start page would be shown (e.g., entering a folder).

Message Composition

A couple of new features have been introduced, causing a different behavior than what you may be used to from Thunderbird 2.0.

Quotes in Replies

• In Thunderbird 3.0, the attribution line in the quotes includes now the date and time of the original message by default (mailnews.reply_header_type=2) [13].
• If you highlight a specific portion (text and/or images) of a message before clicking on Reply, this portion only will be quoted, not the full message [14].
• By default, any inline attachments displayed with a message will not be included in the quote even if View → Display Attachments Inline is checked. To revert to the old behavior of including such attachments, set the new mail.reply_quote_inline preference to "true" [15].

Forwarding and Message Attachments

• Thunderbird 3.0 will forward inline by default now rather than sending messages as attachments [16], thus allowing easier editing of the messages and avoiding attachment-related problems for the recipients.
• If a message is forwarded as attachment, many servers reject message attachments these days based on an ".eml" suffix (file extension) to the attachment name. On the other hand, certain e-mail clients or operating systems rely on the suffix to identify them as such. Thus, there is now a checkbox for a new mail.forward_add_extension preference next to the forwarding mode in the Composition preference pane to toggle the presence of the file extension [17].

Pasting of Images from the Clipboard

• Thunderbird 2.0 allowed pasting of images into the message in lossy JPEG format only, where the low quality was a frequently criticized issue especially on Windows platforms [18].
• While pasting in JPEG will remain an option, the default will be lossless PNG in Thunderbird 3.0.
• Note that the format in which an image was put on the clipboard does not have an impact on how it will be pasted [19]. If you want to retain the original encoding of an image, you would have to save it first and then insert it into your message from a file [20]. Also, drag-and-drop from a file or other message will not recode the image.
• There are certainly cases where you would prefer JPEG instead, e.g., if message size is more of an issue than image quality. Look at the description for the new clipboard.paste_image_type preference for the options [21]. Both PNG and JPEG are supported by the clipboard mechanisms of all major platforms, GIF is not available on Windows or Linux.
• For JPEG, the encoding quality is determined by the operating system or hard-wired in Windows, thus not configurable [22]. A patch to increase the encoding quality on Windows from 50 to 92 is pending [23].Note that the workaround of editing the Windows executable to modify JPEG-encoding quality does no longer work in Thunderbird 3.0.

Content Disposition of Attachments

• The default for the content disposition has been changed from inline to attachment, thus such attachments are no longer marked for display with the message but as "true" attachments, even if they are image or text which could be displayed with the message [24].
• While this resolves some problems met with the previous default, it may not be your intention, thus set mail.content_disposition_type to 0 to revert to the old behavior.
• Note that Gmail will not display forwarded message attachments with the new default content disposition correctly [25].
• Since just switching the default is not a satisfactory solution for all cases, this is subject to further investigation how the disposition can be determined from the attachment type or user interaction [26].

Encoding-Related Changes

• When writing a message which contains characters not representable in the default encoding, a dialog box used to pop up asking wether to send in UTF-8 (Unicode) instead. This was considered confusing, especially for users not aware of the technical details.
• Up-conversion to UTF-8 is now performed silently without asking the user [27]. This also resolves a couple of other issues, e.g., that dialog popping up during autosave of the message as draft.
• Another candidate for removing a potentially confusing dialog is "Send as plain text or HTML?" if no other arrangements are made, e.g., in the address book. If approved, the proposed new behavior would be to silently send as both plain text and HTML [28].

Searching

• A new indexing system (Gloda [29] = Global Database) is introduced, which allows better performance when trying to find messages.
• By default, the indexing is disabled for now until all issues are resolved [30].
• This option can be enabled or disabled in the Advanced → General tab of the preferences.
• Integration of Thunderbird message folders so that they are searchable from the Vista Search function [31], similar work in progress for Spotlight Search in Mac OSX [32].

Address Book

• On Mac OSX, searching the address book of the operating system is enabled by default [33], [34].
• The address book has been extended with a field for the birthday, other improvements are pending [35].

Account Setup

IMAP Accounts

• New IMAP accounts are set up with offline folders enabled by default now [36].
• Existing IMAP folders may be quietly marked for offline use [37]. If you don't want to keep offline copies, disable that either in the Account Settings → Syncing & Disk tab, or in the context menu of each folder in the Properties → Offline tab.
• In the Advanced dialog of the Offline tab, you can select multiple folders with the mouse, or use the cursor keys (with Shift held down) to highlight a number of folders, then toggle their offline status with the Space bar all at once rather than individually.
• Note that the retention-policy setting applies to both the local offline store as well as the remote IMAP folder [38].

Connection Settings

• The "SSL" and "TLS" labels in the server settings have been renamed to more accurately reflect the algorithms used. While this is potentially confusing, no change in the underlying algorithms has been performed.
• For the outgoing SMTP server settings, the new labels read "STARTTLS" (formerly "TLS") and "SMTP-over-SSL" (formerly "SSL"), the labels for POP and IMAP settings yet have to be changed [39]. Note that "STARTTLS, if available" is discouraged for security reasons [40].
• The account wizard can determine (or guess) connection parameters from your e-mail address. This is still work in progress [41].

Preference Settings

There are efforts ongoing to clean up the preference panes [42], [43]. Thus far, not much of this has actually been implemented [44]. Some options have been added, others removed, and some moved into different panes of the Options dialog.

Moved Preferences

• The check for default e-mail client now moved to the Advanced pane.
• Various settings of the General tab in the Advanced pane moved into a new Advanced → Display tab.

Add-On Manager

• Similar to Firefox 3.0, the add-on manager can be accessed through the General tab in the preferences.

Removed Preferences

A couple of depreciated or not frequently used preferences were removed from the Options, but are still available as "hidden" preferences through the Config Editor.

Display settings, Fonts dialog:

• "Apply default character encoding..." mailnews.force_charset_override (defaults to false).

Composition settings:

• "For messages that contain 8-bit..." mail.strictly_mime (defaults to false).
• "Wrap plain text messages at..." mailnews.wraplength (defaults to 72).

Advanced settings:

• "Remember the last selected message" mailnews.remember_selected_message (defaults to true).
• "Connection timeout" mailnews.tcptimeout (new default 100).

System Requirements

The system requirements match those of Firefox 3.0 now. This means that Windows versions earlier than Windows 2000 are no longer supported, and Mac OSX 10.4 is needed as a minimum. For Linux, most non-enterprise versions for which the distributor provides current patches should work, e.g., Gtk 2.10 and other more recent libraries are required.

Category:Thunderbird