when i open my mail app it crashes right away

Have you meet this problem when you haven't update to the latest OS version? Maybe it is a bug of the new OS.

close your mail app.Do a reset by holding the power and home button until the apple logo appears ignoring the slide to power off (no data loss).then open youe mail app again

DONT DELETE ANYTHING; you could possibly damage the software! Just sign into your icloud like i did and everything should work just fine!