The following manual describes the way to get your signature to the default Mail app on iOS. If you're looking for the Gmail manual, please follow here.
- Go to the User page on your iPhone or iPad
- Scroll down to the Download HTML option
- Click on it and you'll see your current signature.
4. Tap and hold the signature until the selection tool appears.
5. Choose Select All to highlight the entire signature.
6. Tap Copy.
7. Now launch Settings from your Home screen.
8. Go to Mail.
9. Tap Signature under the Mail section.
10. Delete your current signature
11. Tap Paste to insert the signature you copied from the email.
12. Shake your iPhone or iPad to activate the Undo tool.
(It's possible you have "Shake to Undo" function deactivated. To switch it on, go to Settings->General->Accessibility->Shake to Undo and toggle it on).
13. Tap Undo to remove any automatic formatting and bring back color or content from the original paste.
Your signature is ready and will now appear at the bottom of emails sent from your iPhone or iPad.