8.2.1. Signing a message

You are now ready to write your first digitally signed email message. From your email client, click on the Compose button as you normally would do. You will notice two new gadgets on the Compose window: a OpenPGP icon on the toolbar, and small icons of a pen and a key on the bottom right corner.

The OpenPGP icon behaves both like a button and a drop-down menu. From there, you can select the options Sign Message and/or Encrypt Message. You can select the same options from the OpenPGP menu item. As you already know by now, you can send a message signed, encrypted, or both encrypted and signed. The pen icon (which means signature) and/or the key icon (which means encryption) lights up to signal that the relevant option is on. The icons work also as toggle buttons, that is, you can also click directly on the pen and the key icons to respectively toggle signature and encryption.
The following figure shows the composition of a signed message:

Select the option Sign Message and click Send. The message will be signed with the key specified in the Account Settings for the account you're currently using (the one shown in the From: drop-down menu).
You will be asked for your passphrase, which is necessary for all operations concerning your private key such as signing messages, decrypting messages, and revoking or modifying properties of your key pair. It is also possible to cache your passphrase for a chosen amount of minutes so you won't have to type it every time: this can be set from OpenPGP → Preferences → Passphrase settings and is explained in detail in Section 9.1.1.
At the time of sending, your mailclient might complain that the message you composed contains characters not found in the selected Character Encoding, and ask you to choose between different options. In this case, the best choice is Send in UTF-8.