Send Later Version History

114 versions

Be careful with old versions!

These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.

Version 10.4.3 627.6 KiB Works with Thunderbird 102.0 - 129.*

If you are using Send Later with Thunderbird 128, you need the "Encrypt" button to be present in your compose window toolbar or you won't be able to schedule messages. If you've removed it, you will need to customize the toolbar and put it back. This is a Thunderbird bug which will hopefully be fixed soon.

Fixed the "Skip next occurrence" right-click menu command, which was deleting the scheduled message instead of skipping its next occurence!

The scheduling pop-up is supposed to remember the previous values when the user edits a previously scheduled message or when the user opens the pop-up, edits its contents, closes it, and opens it again. At some point this fixed. Now it's fixed.

Translation updates.

Version 10.4.2 625.3 KiB Works with Thunderbird 102.0 - 128.*

Thunderbird 125 compatibility

Version 10.4.1 625.4 KiB Works with Thunderbird 102.0 - 127.*

Send Later previously assumed that there could be only one "local" account in a Thunderbird profile, but it turns out that's not the case. Therefore, when we're looking for the user's outbox we need to iterate through all available local accounts rather than just assuming there's one. Otherwise Send Later might not be able to deliver scheduled messages.

Also, some translation updates.

Version 10.4.0 624.9 KiB Works with Thunderbird 102.0 - 126.*


Send Later now obeys the `mail.sanitize_date_header` Thunderbird preference. If this preference is set to true then, as with messages sent directly without Send Later, the `Date` header inserted into scheduled messages upon delivery will be in the UTC timezone and will always have `00` for the number of seconds.

There is a new `autoUpdateDraftsFolders` advanced preference which defaults to false. If you set it to true then whenever Send Later iterates through all Drafts folders it will tell Thunderbird to refresh them. You may need this if you schedule messages on one machine and have another machine deliver them; you probably won't need it otherwise. If you do enable this, you should configure Thunderbird to synchronize your Drafts folder locally because otherwise the performance impact could be noticeable, especially if you have a lot of drafts.

Bug fixes

Many people reported that the Send Later scheduling window was disappearing immediately after it popped up when they clicked on the Send Later button in a compose window. This appears to be due to a bug in Thunderbird. As a workaround, the scheduling window has been modified so that it is no longer "attached" to the button and is instead a separate window which does not exhibit this problem.

We have continued to see consistency issues when editing scheduled drafts and rescheduling them, e.g., the changed content or schedule not being saved to the IMAP server, old versions of the draft continuing to appear in the Drafts folder, etc. These issues have been observed most frequently with Gmail but may also occur with other types of mail server. Two changes in Send Later have been introduced in this release to attempt to mitigate these issues:

  • Each time a draft is saved it is assigned a new messages ID (this was the behavior of the add-on before it was inadvertently removed by the previous maintainer).
  • We now compact the Drafts folder each time we save a scheduled draft.

Version 10.3.6 618.5 KiB Works with Thunderbird 102.0 - 123.*

In release 10.3.5, I added code to tell Thunderbird to update its index for folders when scanning them for scheduled drafts. This caused an unexpected problem I've been hearing about from a number of people: repeated password prompts for accounts that people don't save their passwords for in Thunderbird's password manager.

To avoid this problem, I'm pulling back and only updating folders while waiting for just-saved drafts to appear in them.

Version 10.3.5 618.3 KiB Works with Thunderbird 102.0 - 123.*

Bug fix release.

Fix a bug which was sometimes causing scheduled messages not to save properly.

When throttleDelay is used, throttling shouldn't happen until after the draft that was just sent is deleted. Otherwise if the next main loop starts before the throttle delay is over, we'll get the corrupt drafts folder pop-up, because the draft has been locked but not yet deleted.

Fix another bug which was preventing throttleDelay from working properly (messages were being sent more quickly than throttleDelay said they should be).

When we tell the user that the original draft wasn't deleted because rescheduling it failed for some reason, then don't delete it!

Italian translation updates.

Version 10.3.3 617.0 KiB Works with Thunderbird 102.0 - 120.*

See full release notes. Highlights;

  • The Send Later pop-up in the main Thunderbird window now shows which folder each scheduled draft is in.
  • Send Later now supports internal logging in addition to the console log, which is useful (among other things) for troubleshooting Send Later issues that persist across multiple Thunderbird sessions.
  • Translation updates.
  • Make it possible for Send Later to successfully locate scheduled messages when a folder has been configured by the user to store both Templates and Drafts.
  • Alert at delivery time when a message is too large for Thunderbird to deliver.

Version 10.2.10 602.2 KiB Works with Thunderbird 102.0 - 120.*

See the full release notes here.


You can now subscribe to a beta channel to get new features early and help us find bugs.

You can store scheduled drafts in a subfolder of your main drafts folder.

Return receipts work now.

You can now move scheduled drafts easily from one Thunderbird profile to another.

You can disable shortcuts and remove them from the scheduling pop-up.

You can change the key bindings for the shortcuts.

You can now designate an address book whose members should bypass "Send delays messages" and "Send does Send Later".

Send Later is now smarter about figuring out which identity to use when sending a message, which means you no longer need to worry about your identities being configured in the same exact order when sharing scheduled drafts among multiple Thunderbird profiles.

There are more improvements to date parsing which we hope will completely eliminate the problem of the scheduling pop-up not working in some locales when you use the date and time pickers.

Version 10.1.9 522.9 KiB Works with Thunderbird 102.0 - 119.*

Fix a date-parsing bug which sometimes prevented Send Later from parsing dates correctly on platforms where the built-in date formatter sometimes puts special space characters (e.g., narrow spaces) in formatted dates.

Fix a bug which sometimes prevented Send Later from parsing dates properly on systems where the user's region settings specified English as used in a country other than the United States, the United Kingdom, Australia, or Canada. This issue was specifically encountered by people using "English (Germany)" as their region setting, but the fix applies to numerous other regions as well.

Resize pop-up notification windows which aren't large enough to display their contents.

Update translations.

Version 10.1.6 521.0 KiB Works with Thunderbird 102.0 - 119.*

Implement a Mail Merge compatibility fix that is compatible with Mail Merge now without waiting for the maintainer of that add-on to change anything.

Add the UI and OS date/time locales to the startup message that logs the Send Later version, to assist with debugging issues.

Version 10.1.5 520.6 KiB Works with Thunderbird 102.0 - 119.*

Fix another cause of scheduled messages not being sent for some users: having an account configured into Thunderbird, with drafts in its Drafts folder, whose server is inaccessible either because it's offline or because the user's account on it is no longer valid. With this fix, even if you have that in your profile your Send Later messages will still be delivered, albeit perhaps a bit delayed. To eliminate even that delay, go into Send Later's advanced preferences and uncheck the account in question in the "Active servers" section.

The scheduling pop-up now estimates more accurately when the message you're scheduling will actually be sent. The pop-up also no longer hangs part-way in when you're typing a send date by hand.

When the user changes Send Later's check interval, i.e., how frequently it checks for messages due to be delivered, the change now takes effect immediately rather than waiting until the current interval (with the old value) elapses.

Fix a bug which was preventing the Mail Merge add-on's integration with Send Later from working properly. There is also a fix that needs to be released in Mail Merge before it will start working again.

Allow message context menu operations (schedule message(s), skip next occurrence) to work on Drafts in the Drafts folder underneath Local Folders.

Version 10.1.3 511.2 KiB Works with Thunderbird 102.0 - 119.*

Fix garbling of UTF-8 messages by Send Later.

Allow S/MIME to be used with Send Later, because S/MIME works properly with it, but continue to disallow PGP, because PGP doesn't.

Remember the zoom level of the pop-up window between invocations.

When the zoom window is detached, i.e., it's Thunderbird 115 and the Send Later button isn't in the compose window toolbar, remember its dimensions between invocations.

When displaying a warning that a message is too late to be delivered, and the units of the message are minutes, round the number of minutes down rather than displaying a long floating-point number.

Translation updates.

Version 10.1.1 503.4 KiB Works with Thunderbird 102.0 - 118.*

Release 10.1.0 broke message delivery on Thunderbird 102. This update fixes that. Sorry!

Release 10.1.0 caused people who don't have PGP or S/MIME configured at all to be unable to scheduled messages. This is fixed.

The change in 10.1.0 not to require the Send Later button to be in the compose window toolbar had to be reverted for Thunderbird 102 due to a deficiency in the add-ons API in Thunderbird 102 that is fixed in Thunderbird 115. This means that for Thunderbird 102 the Send Later button is once again required to be present in the compose window toolbar and will be put there automatically by the add-on when you open a new compose window if it isn't already there.

The "Send Later" header display now works when messages are displayed in their own tabs and windows, not just when they're displayed in the message pane. Also, the Send Later button in the message toolbar, which when clicked tells you when the message is scheduled to be sent, now works in all three of those contexts as well.

The link to the privacy policy from the consent pop-up should point at, not at, and should use Google Translate automatically for non-English locale users.

The text describing the preference controlling whether the toolbar button has text + icon or just text was wrong in languages other than English. The wrong translations have been removed but now they need to be retranslated so people are going to see the English string for a while even in non-English locales.

A few other translation updates, most notably the following one but also others.

Version 10.1.0 498.7 KiB Works with Thunderbird 102.0 - 118.*

This is a HUGE release with far too many changes to capture them all here. You are encouraged to review the full release notes. What follows are just the highlights. Note that when Send Later is installed or upgraded it now opens the release notes for your review directly in Thunderbird!

Anonymous data collection

Starting with this release, Send Later collects anonymous usage data to help us improve the add-on, measure its usage, and identify where to focus our efforts.

We're extremely careful to ensure that there's nothing private or personally identifiable in the data we collect and certainly no information whatsoever about your email or email accounts. We don't even capture your IP address on the server to which the collected data is sent. It's a private server under our exclusive control, and we don't share the data with anyone.

When the add-on is installed or upgraded to the new release you will be asked whether you wish to participate in data collection, but note that it is enabled by default since there is no personally identifiable or private information in the collected data. If you just close the prompt window rather than responding, the add-on will keep asking each time you launch Thunderbird until you answer.

See our privacy policy for additional details, including details about the data we collect and how to change your mind and opt in or out when you've already responded to the pop-up.

Bulk scheduling messages from the message list

You can now select one or more drafts from the message list, right-click or ctrl-click to bring up the menu, and elect "Send Later > Schedule message(s)" to bring up scheduling window and schedule all of these messages at once. When you specify the desired schedule and click the "Send at" button, Send Later opens the selected messages one by one and schedules them as requested.

If one of the selected drafts was previously scheduled, the old schedule is overwritten. If it was previously scheduled in a different Thunderbird profile, it is switched over to being associated with profile in which you just rescheduled it.

Note that you can also use the "Send Now" or "Put in Outbox" button here, which means you can use this to send a bunch of drafts or put them all in your Outbox all at once, rather than editing them one by one to do it.

There are two important caveats for users of end-to-end encryption:

  1. This does not work for messages in accounts or identities which have encryption or signing enabled by default, even if you previously disabled encryption and signing when saving the draft. This is due to a functionality gap in the Thunderbird add-on APIs.
  2. Similarly, if you previously saved a draft with encryption or signing enabled and then schedule it like this, the draft is scheduled without encryption or signing.

Skipping the next occurrence of recurring messages

You can now select one or more scheduled messages in your drafts folder, right-click or ctrl-click to bring up the menu, and select "Send Later > Skip next occurrence" to skip the next occurrence of the selected message(s). For example, if you have a message next scheduled to be sent today at 10:00, and at 9:30 you skip its next occurrence, it is rescheduled to tomorrow at 10:00.

This fails (and logs the failure in the error console, though there is currently no pop-up notification) in these circumstances:

  • Thunderbird is currently offline (unless the "sendWhileOffline" preference is enabled).
  • he message was originally scheduled in a different Thunderbird profile.
  • The message has an "until" date/time that has passed.

Again, this is truly a very small sampling all of the improvements in this release, so you really should read the release notes.

Maintenance and enhancement of Send Later is made possible by Extended Thunder Inc., a non-profit dedicated to supporting free, open-source Thunderbird add-on development. We put a lot of time and effort into Send Later, so we hope that if you find it useful you will consider supporting it. You can make a recurring donation to Extended Thunder through LiberaPay or a one-time donation through PayPal. Donations to Extended Thunder are tax-deductible in the United States as permitted by law.

Version 10.0.4 494.3 KiB Works with Thunderbird 102.0 - 118.*

Deliver messages reliably even when the Thunderbird window is minimized.

Deliver messages reliably with Owl for Exchange.

Prevent the scheduling pop-up from invoking dynamic scheduling functions repeatedly when a dynamic scheduling function is scheduled as the default. This improves the responsiveness of the pop-up, but more importantly, it prevents Send Later from flooding a web API with unnecessary repeated requests when a dynamic scheduling function uses a web API.

Further improve the responsiveness of the scheduling pop-up by reducing other redundant code invocations.

Create a new instance UUID if one doesn't exist on startup. This allows the user to reset the instance UUID (when necessary) by removing the old one in the advanced configuration editor and restarting Thunderbird.

Version 10.0.2 493.0 KiB Works with Thunderbird 102.0 - 118.*

Merge Thunderbird 102 and Thunderbird 115 support into a single release of the add-on, rather than releasing a different release for each Thunderbird version.

FIX: Handle Send Later key command sequences properly on remapped keyboards.

FIX: Make Ctrl-Click and Shift-Click work properly on the Send Later button in the compose window.

If you configure Ctrl-Click and Shift-Click on the Send Later button in the compose window to do something different from a plain click, this now works properly.

FIX: Make Ctrl-Alt-1, -2, and -2 work properly in the compose window.

FIX: use placeholders for explanatory strings in dynamic function editor.

When the user indicates in the dynamic function editor that they want to create a new function, instead of inserted text into the text fields in the editor indicating what each of them should contain, set placeholders for the fields, i.e., grey text that automatically disappears when the user starts typing into the fields.

FIX: Don't duplicate dynamic functions in the pop-up menus for selecting them.

Previously, when you edited and saved a dynamic function, its name was added to all of the pop-up menus even if it was already there. This duplication has been fixed.

FIX: Put the correct link for the user guide at the bottom of the preferences page.

FIX: The warning about quitting with pending drafts shouldn't be displayed when the "sendDrafts" preference is false.

FIX: The Send Later button in the main Thunderbird window should be clickable even when the "sendDrafts" preference is false.

Version 10.0.1 487.3 KiB Works with Thunderbird 115.0 - *

This release provides support for Thunderbird 115. This release does NOT support earlier Thunderbird versions; for those, you need to install the most recent Send Later 9.x release.

Note that it is not possible in Thunderbird 115 for add-ons to add custom columns to the message list, so this functionality has been removed. It will be restored for a later Thunderbird release when it is possible. In the meantime, you can see a list of scheduled messages by clicking on the Send Later button in the main Thunderbird window.

Version 9.3.0 495.3 KiB Works with Thunderbird 102.0 - 114.0

FIX: Improve the reliability of the add-on. There should be very few if any non-deterministic failures now.

FIX: We no longer fail to process some scheduled drafts when there are more than 100 messages in a drafts folder.

FIX: The "getPreferences" command supported by this add-on which allows other add-ons to fetch its preferences now works properly.

FIX: The custom Send Later column in the message list is now properly enabled and disabled when it should be.

FIX: The display of the Send Later row in the message header of the message preview now works more reliably.

Version 10.0.0 494.3 KiB Works with Thunderbird 115.0 - 115.*

Version 9.2.9 494.8 KiB Works with Thunderbird 102.0 - 114.0

Bug fixes:
* Fix compatibility with dark themes
* Improve resiliency to issues during start-up, including more reasonable handling of partially degraded states.

E.g. if some of the UI elements crash, it doesn't necessarily need to crash the whole extension. Conversely, if a core part of the extension fails to initialize, the remaining UI elements should be removed or disabled to avoid misleading the user into thinking the extension is active when it is not.

Version 9.2.7 494.0 KiB Works with Thunderbird 102.0 - 110.0

Optimizations will improve Send Later's performance especially for users with lots of scheduled messages
Bug fixes:
* Fix bug where mailing lists were not being expanded into recipient addresses
* Fix bug where recurring messages were not automatically marked as "read"

Version 9.2.4 493.0 KiB Works with Thunderbird 102.0 - 108.0

* UI tweaks, including moving the status bar indicator to a browseraction button with a popup window
* Several translation strings updated
* Lots of back-end improvements
* Bug fixes

Version 9.0.11 499.1 KiB Works with Thunderbird 88.0a1 - 102.*

Updated some translation strings

Version 9.0.10 502.2 KiB Works with Thunderbird 88.0a1 - 102.0

Fix bugs in BusinessHours function:
1. Some locales (Portuguese and Russian) had syntax errors in the translated version of the function
2. It was possible to inadvertently put the function into an infinite loop by providing "[]" in the arguments field. That would effectively freeze the entire Send Later extension until Thunderbird was restarted.

Version 9.0.9 500.8 KiB Works with Thunderbird 88.0a1 - 102.0

* Fix regression that prevents Send Later from fully initializing.
* Add translations for several languages

Version 9.0.8 499.5 KiB Works with Thunderbird 88.0a1 - 102.0

Fixed a bug that prevented Send Later from running in recent Thunderbird Beta releases

Version 9.0.6 498.7 KiB Works with Thunderbird 88.0a1 - 102.0

Send Later version 9 contains many internal changes from the 8.x branch, but relatively few user-facing changes.

Added features:
* Restore original schedule when editing an existing message.
* Enable customizing they format in which dates & times are displayed.

General improvements:
* A lot of application-specific code has been moved into the sandboxed background context
* Several specialized experiment functions have been replaced with official webextension api's
- e.g. notifications are now created using HTML windows rather than native popups
* Other extensions can now modify the message or cancel sending as they would when the message is being sent normally

Version 8.9.8 484.7 KiB Works with Thunderbird 78.2.0 - 93.0

Set maximum Thunderbird version for Send Later 8.9. Will be moving to 9.0 with next Thunderbird ESR.

Version 8.9.6 484.7 KiB Works with Thunderbird 78.2.0 - 102.0

Bug fix: format internal dates with "Sep" rather than "Sept" for compliance with standards. This fixes issues with pedantic mail servers that reject improperly formatted dates.

Version 8.9.5 484.3 KiB Works with Thunderbird 78.2.0 - 91.*

Fix for compatibility with Thunderbird 91