I can't receive or send emails a message box comes up to say that my btinternet.com is not correct. I have gone into settings to retype my password with no joy!! Any ideas

Have you tried to delete then readd your e-mail info? Sometimes things get corrupted and the best way to fix it is to start over. (It won't delete your account, just off your iPad and once you readd the info your mails will redownload)

iOS: Unable to send or receive email

http://support.apple.com/kb/TS3899

Can’t Send Emails on iPad – Troubleshooting Steps

http://ipadhelp.com/ipad-help/ipad-cant-send-emails-troubleshooting-steps/

Setting up and troubleshooting Mail

http://www.apple.com/support/ipad/assistant/mail/

Server does not allow relaying email error, fix

http://appletoolbox.com/2012/01/server-does-not-allow-relaying-email-error-fix/

Why Does My iPad Say "Cannot Connect to Server"?

http://www.ehow.co.uk/info_8693415_ipad-say-cannot-connect-server.html

iPad Mail

http://www.apple.com/support/ipad/mail/

Try this first - Reset the iPad by holding down on the Sleep and Home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons. (This is equivalent to rebooting your computer.)

Or this - Delete the account in Mail and then set it up again. Settings->Mail, Contacts, Calendars -> Accounts Tap on the Account, then on the red button that says Remove Account.

 Cheers, Tom 😉