Want to add some personality or useful contact details to your ‘Sent from my iPhone’ email signature? You can delete the current signature and type a new one, perhaps including a website link, a Twitter account, or company name. To do this open the Settings app, then tap Mail, Contacts, Calendars and scroll down to Signatures. From there, you can input a custom signature.
If you’ve multiple email accounts, you can change them individually by selecting the Per Account option.