I,ve been using email on my iPad for some months and all has been fine.
Yesterday I started having this problem.
When I click on the email button, it opens for about 3 seconds displaying all the emails including new ones, then it closes itself.
safari is also working fine so my Internet connection is not a problem.
How long has it been since you restarted your device? Restart by holding down the sleep/wake button until the red slider appears.
I had already done that, and I,ve just tried again with no success.
Try going into settings and deleting the mail account. Then restart and see if it opens properly. If it does try re-adding it... You may also have an email that is crashing it so you might also delete any new mail off of the account from your pc so your iPad doesn't try to download it.