This is an excellent and very easy to set up and use plugin. I've used several other contact forms in the past and this is as easy as the best of them and encrypts the message sent as well. It also includes an anti spam field to stop the spammbots. Just follow the video instructions to set up.
What it does:
wp2pgpmail is a simple, anti-spam, contact form with an extra 'encrypt' button. A site visitor types a message in the usual way. Before sending they press 'encrypt' and the message is encrypted using your public pgp key (these can be generated using the Chrome plugin 'Mailvelope' if you don't have PGP or GnuPG). The encryption takes place on the clients device not the server. That is before any part of the message is uploaded on to the internet.
Since so many people are slack about encryption this seems about the simplest way possible to get encrypted messages sent to you. Visitors to your site don't need any extra software or do anything more than press the 'encrypt' button.