How to add a signature in Gmail on my phone?
You should add a signature to each email so that you know who the message is from. This is important if you are sending mail from a company account that is not signed with your name. An email signature is text, such as contact details or a favorite quote, which is automatically added to the end of a Gmail message. You can set an automatic signature that will be added to each message. If you have multiple email accounts in the Gmail application (not just Google accounts), you can set one automatic signature for each email account.