How to sign an outgoing mail (New)
Last modified on 06 February 2020 03:22 PM

StartMail supports the capability to digitally sign your message to another user using your PGP key pair.

Your digital signature serves a similar purpose as a hand-written signature. It authenticates the source of a message.  Additionally, it timestamps and certifies that the content of a message has not been modified. It provides a way to verify the sender's identity by guaranteeing that the person sending the encrypted email is the owner of a private key that matches the sender's email address. More information can be found in our Technical White Paper here.

A user’s private PGP key is used to sign a message. The signature is verified with the user’s public PGP key. In order to verify the authenticity of the sender’s signature, the receiver must have the sender’s legitimate public PGP key.

If someone has access to your private PGP key, they can impersonate you in an electronic message. Likewise, if you have an altered version of someone’s public PGP key rather than the legitimate public PGP key, you can impersonate that person with that altered key pair.

StartMail provides a setting to digitally sign every email, or you may choose to digitally sign an email while composing it.


To sign an outgoing mail, go through the following steps:


  1. Compose a mail and click Sign

    Step 1 in how to sign a mail

  2. A blue border with a sign icon will appear, indicating that you have selected to sign this mail. When you are finished typing your mail, click Send

    Step 2 in how to sign a mail

  3. You will be prompted to enter your PGP passphrase. Enter your PGP passphrase and click Sign and Send

    Step 3 in how to sign a mail

  4. A notification will appear at the bottom of your screen.

    Step 4 in how to sign a mail

  5. Your recipient(s) will see an icon indicating that the sender has signed their mail.

    Step 5 in how to sign a mail



  • To sign all outgoing mail by default, follow the instructions found here.
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