How to digitally sign an e-mail – Updated

UPDATE 2018-05-17: web links are updates.

I made a post in 2009 explaining how to digitally sign an e-mail with FireGPG. Unfortunately, FireGPG is discontinued and no longer supports Gmail. So, we need to do it differently now.

Objective: To sign your out-going emails through an online email provider such as Gmail or Yahoo mail.

Operation Systems: Any.

Browsers: Firefox or Chrome.

Add-on or extension for the browser: Mailvelop (get it from

It works with: Gmail, Yahoo mail, Hotmail, and most other online, email providers.

How to:

  1. Install Firefox or Chrome
  2. Install Mailvelop for Firefox or Chrome (whichever applies to your browser of choice) from here:
  3. Follow the instructions at to know how to use Mailvelop (the instructions there are super-clear; therefore, I won’t reproduce them in here)


  • When you signed your email you wanted to send to, let’s say Bob, you also need to give him your Public key. Only then, he would be able to check your signature in the future to see if that is really your signature
  • Bob, also needs to have a similar set-up on his own computer to check your signature (he doesn’t have to have the exact setting, but something to check the signature with)
  • If you sign your email and send it to Bob, and if Bob doesn’t have your Public key or if he doesn’t have any program to check your signature with (such as the ones you used to sign your email with), then he will see a bunch of random-looking characters under your email. But, he will not be able to tell if that is your signature, or if it is a valid signature of yours

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