How do I have the year automatically displayed at the bottom of my email?

Answer:

You would have to create a new snippet in the Account Settings -> Snippets. 

Click on "create snippet" and put the following parameter:

Name: Current year.

Description : Shows the current year

Code: {{date 'yyyy' message.sendtime}}

Afterwards, you will automatically find the snippet in the right menu of the email editor, under the icon "*A" Attribute tags, under the name {{snippet "Current year"}}. 

This way you can copy-paste it in the desired place in your communication.

Here’s more information on snippets.