Create a Gmail signature
An email signature is text, like your contact information or a favorite quote, that’s automatically added at the end of Gmail messages as a footer.
Add or change a signature
You can put up to 10,000 characters in your signature.
In the top right, click Settings Settings.
In the “Signature” section, add your signature text in the box. If you want, you can format your message by adding an image or changing the text style.
At the bottom of the page, click Save Changes.