Digital Signature is an in-built function using which you can set a specific text to be sent with every email you send. Here's the step-by-step method to set up a mobile digital signature through the Gmail app.
1. Open your Gmail app using your phone.
2. Tap on the "Three dashed" button or burger button and scroll down to settings with a gear icon.
3. If you've set several accounts for Gmail, you have to choose the account for which you want the digital signature to set. I here am doing It for my official e-mail firstname.lastname@example.org.
4. Then at the most bottom, you'll see an option with "Mobile Signature" written on it.
5 Write the desired signature which you want, says Tech Aficionado, and tap OK.
6. Now your digital signature has been set. Compose an email and your digital signature will be shown at the end of every email.