Send Later Version History

22 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 4.4.4 154.1 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Bug: Fix Send Later column after using quick filter

Previously, if you used the quick filter bar to search messages in the Drafts folder, then the Send Later column would stop working. This is fixed.

Bug: Fix incompatibility with the Mnenhy add-on

Recent necessary changes made Send Later incompatible with the Mnenhy add-on, because Mnenhy replaces certain core Thunderbird components. Send Later now has a workaround for this problem.

Version 4.4.4beta2 154.1 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Work around problems caused by Mnenhy add-on:

The Mnenhy add-on replaces the Thunderbird header display pane with one of its own, which causes Send Later -- which overlays its functionality on top of the standard Thunderbird header display pane -- to malfunction. This, in turn, causes Mnenhy to malfunction, thereby causing problems with message display.

This change mitigates this problem by suppressing the exceptions within Send Later caused by Mnenhy's UI changes. The Send Later functionality for automatically hiding or displaying the x-send-later-at header as needed still doesn't work with Mnenhy, but at least everything else should work after this change.

Version 4.4.3 153.8 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Bug fix: If the user runs Thunderbird when the system clock is incorrectly set in the future, and then subsequently the system clock is fixed, Send Later would stop delivering scheduled messages.

Bug fix: Don’t display the “Every” checkbox in the Send Later prompt window when it’s not relevant.

Bug fix: Before this fix, Send Later was sometimes causing displayed message headers to be aligned incorrectly.

Bug fix: Replace a reference to “Send Later 3″ in the user interface with “Send Later”.

New Brazilian Portuguese translation, thanks to wetabax from BabelZilla.

Non-functional (invisible to users) changes to make the add-on validator happy.

Upgrade SugarJS date-parsing library; this change should be invisible to users.

Version 4.4.1 154.8 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Compatibility fix for Thunderbird 37+.

Version 4.4 154.7 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

All the shortcut keys in the Send Later prompt window mentioned in the user guide now work in Mac OS, using the Mac OS command key as for other standard Mac OS shortcut keys.

On other platforms (e.g., Windows, Linux), the key for activating shortcuts has changed from Alt to Ctrl.

The Ctrl key is what we should have been using all along, but we were using Alt instead for historical reasons. In order to make shortcuts work on Mac OS, we need to standardize on the "correct" shortcut key on all platforms, hence the change on the other platforms.

Version 4.3.1 154.6 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Fix the accelerator keys for the shortcut buttons, i.e., you can now type Alt-1, Alt-2, or Alt-3 in the Send Later dialog to activate the first, second, or third shortcut button. This has been broken for over two years, but no one reported the problem until recently!

Update the Japanese translation. Thanks, as always, to my awesome translators!

Eliminate some unnecessary error log messages showing up in the error console. If you never look in the Thunderbird error console, this has no impact on you. ;-)

Version 4.3 154.5 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Changes since release 4.2.4:
  • Send Later now warns you on exit if you have pending messages scheduled to be sent, to help you avoid accidentally quitting when you meant to leave the application running so it could send the messages. There is a checkbox in the message you can uncheck if you don't want to be warned again.
  • It is once again possible to use local mailing lists in scheduled messages. This functionality was broken by a recent Thunderbird release but is now fixed.
  • Translation updates. Thank you as always to my translators, including new translator Kari Eveli!
  • More robust performance in foreign languages.
Changes since release 4.2:
  • Scheduled messages are no longer sent repeatedly when the Drafts folder is corrupted. Instead, when Send Later encounters a message in the Drafts folder that it has already sent, it displays an error notifying the user that the Drafts folder needs to be repaired.
  • The X-Enigmail-Draft-Status header is now removed from scheduled messages before they are sent by Send Later.
  • Compatibility with Thunderbird 26+ and Seamonkey 2.23+.
  • Some debug log messages generated by Send Later have been downgraded in priority to make them easier for folks who care about such things to ignore them.

Version 4.2.4 151.0 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Remove the "X-Enigmail-Draft-Status" header before sending a scheduled message.

French and Dutch translation updates. Thanks, as always, to my translators!

Version 4.2.3 150.5 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Add a workaround for a Thunderbird / Postbox bug which occasionally causes Send Later to send messages multiple times.

Version 4.2.2 149.5 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Fix compatibility with old Thunderbird versions. Sorry about that!

Version 4.2.1 149.5 kB Works with SeaMonkey 2.21a1 and later, Thunderbird 24.0a1 and later

Compatibility with Thunderbird 26+, SeaMonkey 2.23+.

Dutch and Finnish translation updates (thank you to my translators!). NOTE: I need a new translator for Traditional Chinese (zh-TW). If you're interested in helping out, please let me know (email! Thanks!

Fix home page URL.

Version 4.2.0 149.0 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Changes since 4.1.7:

When the user clicks on the "Put in Outbox" button, a warning now pops up explaining what that button does and why the user might actually want to click on the "Send around" button instead. There is a check-box in this pop-up to prevent it from being displayed in the future. The purpose of this new warning is to help alleviate the confusion from which some users suffer about which button to click to schedule a message.

New Armenian translation. Thanks to HrantOhanyan from BabelZilla!

Version 4.1.7 141.0 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

  • Traditional Chinese (zh-TW) translation from Mike. Thanks to Mike and all my other translators!
  • Updated date-parsing code (version 1.3.8 of SugarJS), including some improvements to French date parsing.
  • Postbox compatibility updates; Send Later now requires Postbox 3.0.6 or newer.
  • Update compatibility range for SeaMonkey and Thunderbird.

Version 4.1.6 139.9 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Compatibility with Thunderbird 20+.

Version 4.1.5 139.2 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Hebrew translation from Shai65 at BabelZilla. Thanks, Shai! Note: Hebrew date-parsing doesn't work yet, so all you Hebrew users will still need to type your dates in English.

New version of SugarJS with updates to date-parsing.

Version 4.1.4 134.0 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Bug fix: Fix the Dutch, Finnish and Swedish translations to reflect the fact that the check interval preference is now minutes rather than milliseconds. I'm not sure how updating these particular translations got overlooked when this functionality change was made. Sorry!

Enhancement: When Thunderbird encounters an error sending unsent messages (i.e., delivering messages from the Outbox after Send Later has put them there), log the error in the error console, to assist in debugging what is causing it (which, to be clear, is a Thunderbird problem, not a Send Later problem).

Enhancement: Update the Swedish translation.

Enhancement: Update the URL of the user guide in error messages (the old URL works but is deprecated). Also, add the user guide URL to a Finnish error message that was missing it.

Non-functional: In the source code for the add-on, comment out a function that is only used during testing so that the add-on validator on doesn't complain about it.

Version 4.1.3 134.0 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Bug fix: A bug was introduced in version 4.1.2 which caused recurring messages to fail to be rescheduled after being sent. If you use recurring messages, check to see if any of them have disappeared from your Drafts folder, and if so, put them back by copying them from Sent Items and rescheduling them!

Enhancement: Add access keys for the "Put in Outbox" button in the prompt window. You can now type Alt-O (or the equivalent in other languages) to activate the button.

Bug fix: Dynamic recurrence functions should be able to return Date objects, not just numbers of minutes.

Version 4.1.2 133.7 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Fix bug introduced in version 4.0.7: Don't send scheduled messages twice!

Bug fix: The scheduled send time was not being calculated properly when it was entered using the date and time pickers, and the keyboard rather than the mouse was used to change their values.

Enhancement: Dynamic shortcuts can now implement recurrence! See

Enhancement: Make explanatory text appear inside the text box in the "Customize Toolbar" window so that it's clearer that the text box is for Send Later.

Bug fix: In rare cases Send Later was failing to notice scheduled drafts.

Bug fix: Various date parsing improvements from Andrew Plummer, the author of SugarJS, the date parsing library used by Send Later.

Bug fix: Don't cause "Error Copying Message to Drafts Folder" when hitting Ctrl-Enter in the text box in the pop-up window, or when clicking on the shortcut buttons in the toolbar.

Bug fix: Do not allow Enter or Ctrl-Enter to work when valid time has not been entered.

Enhancement: Dynamic shortcut buttons can now return a Date object rather than the number of minutes into the future.

Bug fix (non-functional): Use closures instead of script fragments for event listeners, as suggested by AMO editors. See

Version 4.0.6 130.7 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

NOTE: If you had Send Later in your compose window toolbar prior to this release, you will have to add it back. The toolbar customization mechanism has changed in this release. It’s better now, but it’s incompatible with the old mechanism. See the user guide for details.

Enhancement: Change the add-on's name from "Send Later 3" to "Send Later", translated for every supported language. The add-on was previously named "Send Later 3" because there was an old "Send Later" add-on with similar functionality for old Thunderbird versions, but that add-on has not been maintained for years and is no longer even available on, so it is time to take its place.

Enhancement: Add back the ability to choose the date and time using the mouse using date and time pickers, instead of or in addition to use free-form text input.

Enhancement: Each of the add-on's compose window toolbar items can now be added and positioned separately, giving the user complete control over the items appearing in the toolbar. Furthermore, the user can choose whether to put free-form text input, date/time pickers, or both in the toolbar.

Enhancement: Since the shortcut buttons are now added or removed by customizing the compose window toolbar directly, there are no longer checkboxes in the add-on's preferences controlling whether the buttons appear in the toolbar.

Enhancement: Change the "SENDLATER3" status tag at the bottom of the main Thunderbird window to match the add-on's name in every language.

Enhancement: Add a Chinese description to the install manifest, so that the description that shows up in Tools | Add-ons for Chinese users will be in their native language.

Bug fix: The Send Later button in the pop-up prompt window is now activated, as it should be, when the window first comes up when re-scheduling a previously scheduled draft.

Bug fix: Prepopulating the scheduled send time when editing a previously scheduled message was not working in some circumstances.

Bug fix: The schedule button in the toolbar was not always being updated properly with the scheduled send time.

Enhancement: Improvements to Dutch date parsing.

Bug fix: If user has OS configured with custom date format, then sometimes the prepopulated scheduled send time inserted when editing a previously scheduled message is not understood by Send Later 3!

Bug fix: Add missing space after typo in error message.

Version 4.0.4 132.1 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

Enhancement: Add Dutch date parsing.

Bug fix: Some users have been seeing "Drafts folder may be corrupt" errors repeatedly, even after repairing all of their Drafts folders.

Bug fix: In recent (not yet released to the general public) versions of Thunderbird and SeaMonkey, displaying the release notes after updating the add-on was not working properly.

Bug fix: When editing a previously scheduled recurring message, the text box and button in the toolbar are supposed to be disabled because recurring messages can only be scheduled from the pop-up dialog. However, they were not being disabled as they should have been. This is now fixed.

Bug fix: In recent (probably not yet released to the general public) versions of Thuderbird and SeaMonkey, when the user edited a previously scheduled draft and then immediately tried to close the message compose window without actually making any changes to the draft, Thunderbird was asking the user whether to save the draft, even though it was unmodified and didn't need saving.

Version 4.0.3 131.1 kB Works with SeaMonkey 2.9 and later, Thunderbird 8.0a1 and later

I am very excited to announce release 4.0.3 of Send Later 3!

This release includes four major enhancements which have been requested by users more than any others.

Before describing the changes in this release, I want to give a huge shout-out to Andrew Plummer, the maintainer of the SugarJS library upon which much of the functionality in the new release depends. I also want to give a huge round of applause to my translators who have helped to make this release great. They are:

  • Dtrieb from BabelZilla (de)
  • Erwin D. Glockner (de)
  • urko from BabelZilla (es-ES)
  • Samtron-Translations (fi-FI)
  • Bigpapa from BabelZilla (fr)
  • Cesare from BabelZilla (it-IT)
  • Amigomr from BabelZilla (ja-JP)
  • markh from BabelZilla (nl)
  • Maciej Kobuszewski (pl)
  • Mikael Hiort af Ornäs (sv-SE)
  • Wang.H.K from BabelZilla (zh-CN)

Free-form date/time entry

The date and time for scheduling a message are no longer entered using clunky drop-downs. Instead, you just type in the date and time you want, and Send Later 3 parses what you typed and figures out what you meant.

Date parsing is currently supported in the following languages: English, French, German, Italian, Spanish, Portuguese, Swedish, Russian, Polish, Japanese, Korean, Simplified Chinese, and Traditional Chinese (contact me about adding support for additional languages). The add-on first attempts to parse dates using the language indicated by your locale, and if that fails, it falls back on English.

Date parsing understands all sorts of interesting syntaxes in addition to conventional date/time entry. For example, "the day after tomorrow", "next Thursday at 15:00", "the beginning of next week", etc. Date parsing in Send Later 3 is provided by the most excellent SugarJS library, created and maintained by Andrew Plummer.

Because such interesting date syntaxes can be ambiguous, Send Later 3 tells you what it thinks you meant by parsing your text in real-time and showing in the send button when the message will be sent.

This new functionality also makes it easier to schedule multiple messages at the same time, something which has been frequently requested. Rather than being forced to painstakingly selected the same values in the drop-downs over and over, you can simply copy the desired date/time into your clipboard and paste it into the date/time entry field of each message. Add the field to your toolbar to make it even faster!

Enhanced recurring messages

When scheduling a recurring message, you can now indicate a count in addition to a unit. In other words, whereas before you could specify only daily, weekly, monthly or yearly, now you can specify every 3 days, every 5 weeks, etc.

Furthermore, you can schedule monthly messages on the same week and day of every month, e.g., "the third Tuesday of the month."

SeaMonkey support

Send Later 3 now supports SeaMonkey!

Support for the Mail Merge add-on

Starting with its version 3.4.0, the Mail Merge add-on supports Send Later 3! Instructions for using Mail Merge with Send Later 3 can be found here.

(Note: Just to be clear, support for Send Later 3 in Mail Merge required changes to Mail Merge, ​not​ changes in Send Later 3. I'm not trying to take credit for the most excellent work of the author of the Mail merge add-on; I'm just letting people know that you can now use Mail Merge with Send Later 3.)

Other changes

In addition to the major enhancements described above, there are also a number of other changes in this release:

  • There is a bug in Thunderbird 15 that breaks Send Later 3. This release includes a workaround for the bug.
  • The "Send Later" column now displays properly in the unified Drafts folder.
  • The color changes to the Send Later 3 pop-up window, which a number of people described as "garish" and did not care for, have been removed. These are no longer necessary now that the UI has been simplified and made clearer in other ways.
  • The preference for controlling how often to check for messages whose scheduled send time has arrived has been changed from milliseconds to minutes, which makes a heck of a lot more sense.
  • The pop-up window that requests donations for Send Later 3 has been changed so that it no longer has the potential to cause Thunderbird to hang on some platforms. This hang is due to a Thunderbird bug, not a bug in Send Later 3, but since the Thunderbird bug has not yet been fixed, it is important to work around it in the add-on.
  • A bug which was causing recurring messages to be marked unread in the Drafts folder has been fixed.
  • A workaround has been introduced in the code which should reduce the frequency of Send Later 3 complaining about a corrupt Drafts folder, specially when using POP3 or local folders.
  • Send Later 3 now replaces the message ID in outgoing messages so that it does not inadvertently send multiple, different messages with the same message ID (relevant for both recurring messages and messages scheduled from templates).
  • Send Later 3 now correctly expands mailing lists (from your address book) before scheduled messages are saved in the Drafts folder.
  • A hidden preference extensions.sendlater3.logging.filter has been added to optionally specify a regular expression indicating which messages should be logged.

Version 3.3.10 99.3 kB Works with Thunderbird 2.0 and later


The next version to be released after this one will include significant new functionality which cannot be implemented within Thunderbird 2 or Postbox 2. Users who do not wish to upgrade to a newer version of Thunderbird or Postbox may continue to use this version as-is, but there will be no further bug-fix or feature releases compatible with Thunderbird 2 or Postbox 2.