Often it is even simpler than that. For encrypted e-mail using an e-mail client (such as Thunderbird with Enigmail) for addressees with known PGP-keys, hitting

Often it is even simpler than that. For encrypted e-mail using an e-mail client (such as Thunderbird with Enigmail) for addressees with known PGP-keys, hitting the 'encrypt' button and entering your passphrase is all that is needed once all is set up. Decrypting means you get prompted to enter your passphrase, and that's all there is to it.