To write an encrypted email, you will need the recipient's public key. To do so, you can
invite him to Encrypted Communication, or add him by hand. See Inviting Contacts.
Your email is being sent. You can view it in
your Sent folder on any device set up with your key pair.
In your inbox, click the lock icon next to the compose email button.
You will see the usual Compose Email with your
custom mailvelope background.
Add one or more recipients. You can add recipients set up for encrypted
communication, marked with the grey lock icon.
Compose your email as usual. Feel free to add attachments up to 10 MB.
Click Send Encrypted.
If asked, enter your passphrase and confirm with OK.