The arrival of Thunderbird 147 marks a new stable version from Mozilla's popular open-source email client, which also integrates chat, address book, calendar, and news reading. This update focuses primarily on refine the daily user experience, correcting errors carried over from previous versions and adding small adjustments that facilitate the management of large volumes of email.
In a context where many users rely on cross-platform email clients for work and personal communications, this version aims to improve both stability and usability. While not a revolution in terms of features, Thunderbird 147 introduces Practical changes to folder view, overall performance and the reliability in sending and searching for messages.
New features in folder viewing and organization in Thunderbird 147
Among the main new features of Thunderbird 147 is an option to display the “full path” of the folders in compact view modes. This improvement makes it easier to navigate when working with complex subfolder structures or multiple accounts, which is common in professional environments or for users who manage several mailboxes.
The update also introduces the new preference mail.useLocalizedFolderNamesThis setting allows you to enable or disable the localization of special folder names (such as Inbox, Sent Items, Drafts, or Archive). With this option, you can choose whether to see these names translated into your language or keep the original server names, which is useful in mixed environments or when sharing configurations across different systems.
In addition, support is incorporated so that the special folders are located only based on a restricted set of names. This measure aims to prevent confusion and unusual behavior in installations where email providers use specific names for folders such as spam, trash, or archive, reducing conflicts when synchronizing with Thunderbird.
Corrections in folder management and compaction
Thunderbird 147 solves several problems related to the simultaneous compaction of multiple foldersThis is a key task for freeing up space and improving performance in accounts with a large message history. This review aims to make the process more reliable and less prone to internal errors.
The behavior has also been adjusted to Restore manual subfolder orderThis could be confusing when users reorganized their folder tree and needed to revert to the default sorting. The update also improves the management of unified archive subfolders, making archiving structures more consistent across different accounts or identities.
Another aspect reviewed is the visualization of folders with very deep hierarchies and long nameswhich in some cases caused display or navigation problems. Likewise, bugs have been fixed when moving saved search folders or virtual folders within IMAP accounts, a feature used by those who filter and group their email using complex criteria.
Thunderbird 147 introduces improvements to search, filters, and user experience
The function “Search for messages” It has been adjusted to deliver more consistent results and a smoother interaction, which is especially useful when working with mailboxes containing many years' worth of accumulated emails. It has also fixed issues that prevented the selected status and priority from being displayed correctly in certain search widgets, making it difficult to filter or review specifically marked messages.
This version fixes bugs that made it difficult to creation of message filters in the Japanese localeThis correction, although it directly affects that language, is part of the overall effort to maintain compatibility and proper functioning of Thunderbird in various regional configurations.
The search function for the term has also been improved. “Attachment” within the Settings menu to more easily locate the “Files and attachments” section. These kinds of small usability changes help both new and advanced users find key options without having to wade through multiple menus.
Updates to OpenPGP security and encryption
Managing signed messages using OpenPGP It also receives attention in Thunderbird 147, continuing changes initiated in Thunderbird 146The "Open and display" option for signed messages stored as files .eml It has been refined to make the process clearer and less prone to errors, thus reinforcing reliability when working with encrypted or verified communications.
Along with these specific improvements, Mozilla incorporates in this version several security fixes which are not detailed in depth in the summary note, but which are part of the project's routine maintenance.
Performance, stability and handling of IMAP and EWS
Thunderbird 147 includes important adjustments in handling virtual folders in IMAP accounts based on the maildir format, both remote and local. Moving these folders has become more reliable, resulting in better advanced email organization without the risk of losing settings.
Several protocol-related errors have been corrected EWS (Exchange Web Services), used mainly in corporate environments; among them, an improvement in the management of HTTP 500 backoff errors, reducing unnecessary retries and avoiding blockages, as well as the correction of a problem that caused unexpected closures when emptying the EWS trash.
It also resolves a a failure that could cause the program to shut down By marking all messages as read, a common action when quickly cleaning up full inboxes, Thunderbird has been fixed. Similarly, a crash that occurred during Exchange address account setup has been resolved, directly affecting those integrating Thunderbird into enterprise infrastructures.
Email sending and SMTP behavior
One of the most relevant practical points is the correction of a problem that caused the Sending emails via SMTP will be blocked This could be especially frustrating for professional users who send several emails in a row and see the process stop for no apparent reason.
The update also fixes a bug that caused a very slow startup when there was a large number of folders who did not use subscriptions. For users with complex structures or large IMAP accounts, this improvement can be noticeable in the daily startup of the client, reducing the waiting time when opening Thunderbird.
Within task management, a bug that affected the creation of tasks with a start or due daterestoring behavior consistent with what the user expects from the calendar and personal organization part integrated into the application.
Account Hub, interface and other usability settings in Thunderbird 147
El Account HubThe wizard responsible for facilitating account creation receives specific improvements when configuring EWS accounts with OAuth2 authentication. These adjustments help simplify the setup of new corporate accounts, an increasingly common scenario in companies that combine Microsoft services with open-source tools.
Furthermore, a bug in the feeds icon This could prevent RSS feeds from updating, a feature some users employ to follow news or blogs directly from their email client. With this fix, the news feed now behaves more predictably.
The version also includes various visual and user experience improvementsThese changes, while not always spectacular, are aimed at refining interface and navigation details. They typically include minor adjustments to menus, icons, or status messages, which together make the program more user-friendly and intuitive for everyday use.
Finally, the behavior of the command-line option “compose”This is used to open message composition windows from scripts or external applications. This is relevant for advanced users and administrators who integrate Thunderbird into automated workflows.
With all these changes, Thunderbird 147 is presented as an update focused on the stability, performance, and refinement of existing functionsRather than focusing on major, visible new features, installing this version offers a more robust user experience, clearer folder management, and fewer errors, ultimately resulting in fewer interruptions and smoother workflow.
