You really need to provide more information: 1) What email server(s) (e.g. Yahoo, Gmail, Exchange, Web-based, etc.) are you using? 2) Do the emails that you send from your PC and your iPad reach others? and 3) How is your account(s) configured on your iPad (esp. POP3/IMAP & SMTP settings)?
Plus, is this a 'new' problem or has the issue been there from the start of you ownership - if a recent problem, you might want to 'Restart' (and if not effective 'Reset'), the iPad - good luck and let us know your results.