Add or change a signature
You can put up to 10,000 characters in your signature.
- Open Gmail.
- In the top right, click Settings
.
- Click 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.
<source: https://support.google.com/mail/answer/8395?co=GENIE.Platform%3DDesktop&hl=en>