Digitally Sign Emails - Mozilla Thunderbird

Apr 14, 2025

Digitally Sign Emails - Mozilla Thunderbird

  1. Open a new email window in Mozilla Thunderbird. Go to Tools > Account Settings.

  2. Click the Security tab. Click Select next to the Digital Signing field.

  3. Choose the certificate you intend to use for signing. Click OK.


    Note: If no certificates are present, it still needs to be imported. Follow these instructions and then return to this article to continue.
  4. You can choose the encryption certificate here as well:

  5. To sign all messages, check Digitally sign messages (by default) under the Digital Signing field:

    Digitally Sign Messages
  6. Click OK to complete. 

    If you are not signing by default, proceed to the next step for instructions on signing a single email.
     
  7. When composing a new email in Thunderbird, click the Security drop down menu and choose Digitally Sign This Message.


    Note: To send encrypted messages, you must first receive a digitally signed email message from the recipient.

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