I need a way to make thunderbird prevent me from sending mails by mistake. For special, important mails, I would like to be able to individually block the send button, or make thunderbird ask me for confirmation before sending. This locking should not be standard behavior, nor should it be activated automatically based on some rules, I just want to use it for special emails.

What I do so far is to leave the subject or the receipients empty till the mail is finished, such that thunderbird would ask me for these info when accidentially sending. However this is very impractical when replying to messages.


Based on the "better late than never" principle: using the Correct Identity extension, you could configure a nonsense address that, if included as recipient, prompts an extra confirmation.

This would allow you to flexibly 'request' the extra confirmation by adding that address as recipient. For example, you can add "demand@extra.confirmation" in the "Safety" list (or simply 'confirmation'). Prior to sending, the extension checks for matches to that list, and requests extra confirmation if a match is found.

You could then remove the address again if you're sure you want to send the email.

I admit, it's a work-around, but it works quite well for me.


You might want to have a look at Thunderbird add-ons. For instance, Confirm-Address.

Confirm E-mail address before sending mail

You may also be interested by Flex Confirm Email which seems to include some rule-based mechanism.

Confirm mail address and attachments based on flexible rules.

Finally, if you are familiar with PGP signing and encrypting, you are probably using the Enigmail extension. If so, have a look at its settings: Sending > Confirm before sending > Always.

You can install add-ons through the Tools > Add-ons menu in Thunderbird. Here is a link to the search results I used (Mozilla Thunderbird Add-ons) for this answer, you might find more suitable add-ons there.

  • Thanks! However, your first two suggestions Confirm-Address and Flex Confirm Mail both raise their warnings automatically following some rules based on the email content, but cannot be switched on and off for individual emails. Your third suggestion of an everytime confirmation also would not solve my problem, as I only want to use the functionality in rare cases (otherwise one would just get used to the confirmation which would kill its effect) – flonk Sep 5 '14 at 12:41
  • It would help if you could add to your question the specifics of your filtering. "Special emails" does not give much of a clue... – John WH Smith Sep 5 '14 at 12:48
  • With "Special emails" I dont mean any technical property. Suppose, you are writing an important job application. At this point you decide that this email is very important. Therefore you don't want it to be sent accidentially and lock it. This means I want to activate the protection indivually in the composing process. Sorry if that wasn't clear from the question. – flonk Sep 5 '14 at 13:05
  • btw thanks for improving my question, hope it's clear now. – flonk Sep 5 '14 at 13:13
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    This requires you to mark the email before composing it, which is pretty much what you do when you don't type the subject in. Since this is very specific, I don't think there is an extension for this, and I'm pretty sure Thunderbird has no such functionality. I'll leave my answer for further reference but you may have to make your own extension for that. – John WH Smith Sep 5 '14 at 13:13

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