Send Later Extension [SL8TR]

I use Mozilla Thunderbird. I have been using it for a few years now and I swear by it. I evangelize it to anyone and everyone. And I have my gripes.

Whenever I see something that doesn’t quite match my expectation, I have promised myself, “One of these days I am going to write an extension to solve that problem”. That day is finally here. I have had a major gripe about the “Send Later” function of Thunderbird, innocently enough, I thought it would “Send the email Later”, when I wanted it to… But as many Thunderbird users will realize that is being naive…

So I wrote this extension that extends the Send Later functionality by bringing up a scheduler for the time when the “Send Later” option is chosen (Ctrl+Shift+Enter is the shortcut). The extension saves the message to draft and monitors the messages in the draft folder, when the chosen time arrives it moves the message to unsent and sends unsent messages. From the limited testing I have been able to do, it works. I am going to submit it to Mozilla Dev Center and hope they approve it. Meanwhile it is available here for downloads and updates. You may try it at your own risk, I will try my best to support any user.

Send Later Icon Send Later Extension

You can download the extension from You will need to save it your hard disk and then install it from Thunderbird Extension Manager.

This update fixes many problems experienced by some users as well as adding some brand new features

Instructions for installing:

  1. Right click on the link and choose “Save Link As…” or “Save Target As…”.
  2. Choose a file path on your hard disk. [Desktop/Home folder is fine too].
  3. In Thunderbird, goto Tools -> Extensions or Tools -> Add ons.
  4. Choose Install, locate the the SL8TR.XPI file you saved in step 2.
  5. Restart Thunderbird.

Usage Instructions:

  1. There are many new options, mostly self explanatory, please read the update post on the new features.
  2. The background polling status is shown the status bar as “SL8TR [IDLE]“, if there are messages in the draft folder waiting to be sent later the message reads “SL8TR [PEND 3]” (for e.g.).
  3. If you want to schedule a message to send later, just choose “File->Send Later” (or CTRL+SHIFT+ENTER) after composing an email.
  4. This will prompt you with the time and date in a popup window, select the time and date and Click on “Send at specified time”.
  5. You may also click one of the quick access buttons to use a predefined value like 15 mins later [or use ALT+1 or ALT+2 or ALT+3].
  6. If you want to use the default Thunderbird Send Later functionality you can choose “Passthrough to Send Later”.

Here is a preview of the extension running under Thunderbird on Windows Vista

Send Later Prompt Screenshot

Send Later Prompt Screenshot

And that’s it !!!
For any comments and discussion please visit these posts :

Note: If you are having some problems with version 1.0.0 or 1.0.2 or 1.1.5 PLEASE update to version which fixes many issues