Just like Outlook, your email-enabled iOS device is also capable of adding a signature to the end of your email messages automatically. To add, remove, or modify this signature, follow these instructions.
1. Go to Settings and then go into Mail, Contacts, Calendars. Scroll down about half way down the page until you see Signature, select it.
2. In the Signature menu, select the Exchange account signature (or other account, if applicable).