4.19 Published 23/04/2026

The full change log with screen shots can be found here

Improvements

• Set Minimum Version to Thunderbird 140 to avoid problems with deprecated APIs and to focus on modern Thunderbird versions [issue #418].

  Future development will focus on Thunderbird ESR 140 and the upcoming 153 release. Thunderbird platform changes require replacing legacy features such as preference storage and file access with modern APIs.

  New file access APIs are currently being implemented and may only be available in newer Thunderbird versions. Most development effort over the next three months will be dedicated to this work to future-proof SmartTemplates.

Bug Fixes

• Fixed: Sandbox script stops functioning in Tb 150 beta 3 [issue #417] because the string prototype modification was deprecated in Thunderbird 150.

  From version 149 forward, we require the syntax from() when the variable has no parameters. Chaining of variables can be done using the form (await from()).someStringFunction().

  Added detailed diagnostics for syntax problems with literal parameters ($mail) or missing empty parameters ().

4.18.2 Published 30/03/2026

The full change log with screen shots can be found here

This maintenance release extends compatibility to Thunderbird v151, and adds more theme compatibility improvements.

Maintenance Release 4.18.2

• Compatibility with Thunderbird 151
• more theme compatibility improvements

Maintenance Release 4.18.1

• Compatibility with Thunderbird 150

• Remove unnecessary Warning when changing Identity (often caused by Identity Chooser Add-on) [issue #415]

  Since Thunderbird 131, selecting a different identity for the from address will always set a "modified" flag that signals that the email was edited. This will lead to SmartTemplates unnecessarily warning of potential data loss, even if the user hasn't typed anything.

  This was especially jarring With Add-ons like identity chooser, which forces the user to always select an identity.

  In the new version, SmartTemplates will store a checksum of the contents of the current template and then will compare this with the contents when a new identity is selected. If the contents are identical, then no warning will be shown.

There is a new option in General >> Signatures, which allows adding the correct signature while keeping the text of the email unchanged to avoid work loss.

Improvements

• Enhancement: Import external templates menus from other profile [issue #414]. When opening a smartTemplates.json file from another profile, which is typically stored in the profile/extensions subfolder,this will import the list from the selected editing mode (write / reply / forward or snippets).

All imported menu items are moved to the top of the list in he order read from the file contents.

If the an entry exists with the same name / category, or with the same file path (within the current editing mode), then it will be replaced with the entry from the imported file. So this could also be used to reorganize or rename existing templates.

• Enhancement: Import members of a Named Mailing List from template (using %header.set%) [issue #411].

Example: %header.set(to,"list:listName")% this will read all standard address books (not cardbook) and searches for lists named listName. Uses the primary email address of all members of the list, so you can set to, cc or bcc.

• Support relative file paths for %attach()% [issue #335]
• Improvements for correcting "Lastname, Firstname" [issue #305]
• Added documentation for setting priority to variables window. [issue #412]
• Modernized icons of external template toolbar.

Miscellaneous

• removed Console chatter about Cardbook and any matched address book cards.

4.18.1 Published 20/03/2026

Full Changelog: 4.18...4.18.1

Maintenance Release 4.18.1

• Compatibility with Thunderbird 150

• Remove unnecessary Warning when changing Identity (often caused by Identity Chooser Add-on) [issue #415]

  Since Thunderbird 131, selecting a different identity for the from address will always set a "modified" flag that signals that the email was edited. This will lead to SmartTemplates unnecessarily warning of potential data loss, even if the user hasn't typed anything.

  This was especially jarring With Add-ons like identity chooser, which forces the user to always select an identity.

  In the new version, SmartTemplates will store a checksum of the contents of the current template and then will compare this with the contents when a new identity is selected. If the contents are identical, then no warning will be shown.

There is a new option in General >> Signatures, which allows adding the correct signature while keeping the text of the email unchanged to avoid work loss.

• All menu Icons should now reflect the main theme color [issue #416]

4.18 Published 28/01/2026

The full change log with screen shots can be found here

Improvements

• Enhancement: Import external templates menus from other profile [issue #414]. When opening a smartTemplates.json file from another profile, which is typically stored in the profile/extensions subfolder,this will import the list from the selected editing mode (write / reply / forward or snippets).

All imported menu items are moved to the top of the list in he order read from the file contents.

If the an entry exists with the same name / category, or with the same file path (within the current editing mode), then it will be replaced with the entry from the imported file. So this could also be used to reorganize or rename existing templates.

• Enhancement: Import members of a Named Mailing List from template (using %header.set%) [issue #411].

Example: %header.set(to,"list:listName")% this will read all standard address books (not cardbook) and searches for lists named listName. Uses the primary email address of all members of the list, so you can set to, cc or bcc.

• Support relative file paths for %attach()% [issue #335]
• Improvements for correcting "Lastname, Firstname" [issue #305]
• Added documentation for setting priority to variables window. [issue #412]
• Modernized icons of external template toolbar.

Miscellaneous

• removed Console chatter about Cardbook and any matched address book cards.

4.17 Published 06/01/2026

The full change log with screen shots can be found here

Improvements

• Set Compatibility with Thunderbird 148 - unfortunately the current review policies for Add-ons with "experimental" APIs do not allow us to remove strict_max_version from manifest.json
• Support replying to multiple selected messages with same html template. [issue #379] When multiple emails are selected, the header SmartTemplates button is hidden. Use the dropdown menu on the main SmartTemplates toolbar button to select the reply type and the corresponding template.

Bug Fixes

• Fixed: When set to "Use the external template last selected from the drop-down menu." SmartTemplates did not select the matching template for correct the reply type (reply all, reply list, reply to sender) [issue #409]
• Fixed: when replying to an email that opened from an eml file: no SmartTemplates functionality works [issue #406]
• Intermittently, %spellcheck()% switch doesn't work when loading the template during reply [issue #407]
• Fixed: Reply template unexpectedly removed meta info lines within quoted text [issue #408]

Codebase Improvements

• Consolidated pseudo tags in localisation {P} {/P}, {L} {/L} etc.
• Fixed mismatched closing </div> tags (was </vbox>)
• Trim leading spaces and fix dangling doublequotes in some variables see: combineEscapedParams() c00739a

4.16.4 - Published 25/11/2025

The full change log with screen shots can be found here

Improvements

• 4.16.4: Improved date variables — Fixed unreliable creation of month and weekday names in localized formats. [issue #405]

  • use date directly instead of calculating numeral values and converting to text again
  • converted μs based calculation to ms
  • removed remaining hard coded day / month names (long & shortened forms) from language files

• 4.16.3 - Fixed broken editing function in settings [issue #404]

• 4.16.2 - Fixed a regression with the wrong day name being calculated from the email date.[issue #403]

• 4.16.1 - Improved inserting, updating and reordering template menu entries. Drag and drop is now much more reliable and new items are inserted below the currently selected item.

• 4.16 – made SmartTemplates compatible with Thunderbird 146.

• Added new options to prevent duplicate <style> elements when merging into <head> [issue #399]

• Clarified tooltips for loading and saving account templates: "Save templates (write, reply, forward) for $identity$…"

• The news label when an update to SmartTemplates is downloaded is now disabled by default.
  Bug Fixes

• Brought back the status bar button which was missing in Thunderbird release (Tb 142+) [issue #401]

Codebase Improvements

• Removed calendar string bundling and chrome/content/locale [issue #400]
• Use API method (browser.management.get) instead of AddonManager.getAddonByID to check for Cardbook installation
• Removed createBundle for retrieving forward / reply quote headers
• 4.16.4 - removed remaining hard coded day / month names (long & shortened forms) from language files (messages.json, about 3000 lines)

4.16.3 - Published 21/11/2025

Improvements

• 4.16.3 - Fixed broken editing function in settings [issue #404]

• 4.16.2 - Fixed a regression with the wrong day name being calculated from the email date.[issue #403]

• 4.16.1 - Improved inserting, updating and reordering template menu entries. Drag and drop is now much more reliable and new items are inserted below the currently selected item.

• 4.16 – made SmartTemplates compatible with Thunderbird 146.

• Added new options to prevent duplicate <style> elements when merging into <head> [issue #399]

• Clarified tooltips for loading and saving account templates: "Save templates (write, reply, forward) for $identity$…"

• The news label when an update to SmartTemplates is downloaded is now disabled by default.
  Bug Fixes

• Brought back the status bar button which was missing in Thunderbird release (Tb 142+) [issue #401]

Codebase Improvements

• Removed calendar string bundling and chrome/content/locale [issue #400]
• Use API method (browser.management.get) instead of AddonManager.getAddonByID to check for Cardbook installation
• Removed createBundle for retrieving forward / reply quote headers

4.16.2 - Published 18/11/2025

Improvements

• 4.16.2 - Fixed a regression with the wrong day name being calculated from the email date.[issue #403]

• 4.16.1 - Improved inserting, updating and reordering template menu entries. Drag and drop is now much more reliable and new items are inserted below the currently selected item.

• 4.16 – made SmartTemplates compatible with Thunderbird 146.

• Added new options to prevent duplicate <style> elements when merging into <head> [issue #399]

• Clarified tooltips for loading and saving account templates: "Save templates (write, reply, forward) for $identity$…"

• The news label when an update to SmartTemplates is downloaded is now disabled by default.
  Bug Fixes

• Brought back the status bar button which was missing in Thunderbird release (Tb 142+) [issue #401]

Codebase Improvements

• Removed calendar string bundling and chrome/content/locale [issue #400]
• Use API method (browser.management.get) instead of AddonManager.getAddonByID to check for Cardbook installation
• Removed createBundle for retrieving forward / reply quote headers

4.16 Published on 11/11/2025

The full change log with screen shots can be found here

Some users may have seen a false incompatibility warning after updating from Thunderbird to v142. This was caused by cached compatibility information in Thunderbird, which sometimes fails to refresh correctly. The previous version of SmartTemplates was already fully compatible with 142.

I raised a bug with Thunderbird to fix this: Bugzilla 1986027, please add your observations there if you experienced this problem.

Improvements

• 4.16 – made SmartTemplates compatible with Thunderbird 146.
• Added new options to prevent duplicate <style> elements when merging into <head> [issue #399]
• Clarified tooltips for loading and saving account templates: "Save templates (write, reply, forward) for $identity$…"
• The news label when an update to SmartTemplates is downloaded is now disabled by default.

Bug Fixes

• Brought back the status bar button which was missing in Thunderbird release (Tb 142+) [issue #401]

Codebase Improvements

• Removed calendar string bundling and chrome/content/locale [issue #400]
• Use API method (browser.management.get) instead of AddonManager.getAddonByID to check for Cardbook installation
• Removed createBundle for retrieving forward / reply quote headers

4.15.2 - Published 19/09/2025

The full change log with screen shots can be found here
main change is bumping max version to 144.*

Some users may have seen a false incompatibility warning after updating from Thunderbird to v142. This was caused by cached compatibility information in Thunderbird, which sometimes fails to refresh correctly. The previous version of SmartTemplates was already fully compatible with 142.

I raised a bug with Thunderbird to fix this: Bugzilla 1986027, please add your observations there if you experienced this problem.

Hotfixes 4.15.1

• Fixed a serious regression in New/Answer/Forward templates caused by %cursor% + forced paragraph mode, which could cause parts of the template to appear out of order [issue #397]

Improvements

• 4.15.2 - made compatible with Thunderbird 144.
• Removed unsafe assignments to innerHTML and added code sanitation [issue #393]
• Further improvements to the New button badge 🟠 – to display this streamlined status, open Settings » Licenses. Under 'Updates', enable the option "Do not display news label on update" [issue #396]
• Added optional notification when reusing the last template [issue #395]

Bugs Fixed

• Fixed cursor automatic positioning when using %quotePlaceHolder% in templates
• Fixed %dateformat.current% triggering the warning "NOT SUPPORTED: Replace deferred smartTemplate variable" [issue #394]
• Fixed: Deleted Template Still Appearing and Triggering in SmartTemplates Last Template item [issue #389]