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 set up a signature that shows up only for emails you send from the Gmail app. If you have multiple accounts in the Gmail app, you need to change this setting for each account.
- On your iPhone or iPad, open the Gmail app
.
- At the top left, tap Menu
Settings
.
- Under "Compose and Reply," tap Signature settings.
- Turn on "Mobile Signature."
- Add or edit your mobile signature.
- To save, tap Back
.
.
Settings 
.Tip: If you don't create a signature in the Gmail app, new messages use the signature that you set up on your computer.