Please forgive me if I have misunderstood you question.
If you want to use your contact list - Groups in particular, which are not directly supported by the iPad's native email app - in the 'To:' field of a forwarded email, then there is an app called MailShot, which enables you to manipulate Groups within Contacts and use them in the iPad's email app.
If you meant copying contact information from the iPad's Contact database into the message field of an email, then the only way that I know how to do that - and it's so convoluted that you'd have to be crazy to do it this way - is to sync your contacts with a PC, export the contacts list on the PC as a CSV (comma separated variable) file, then transfer the file back to the iPad. Which begs the question, why wouldn't you have emailed the file from the PC instead? I said it wasn't a helpful suggestion...
Tim
Scotland