I just found and tried this and seems to have worked,
Here's the copy paste
Found on the Apple Support forums:
1. Restore your phone (back it up before restore)
2. Once phone is restored, the iTunes iPhone welcome screen comes on (set up as new account, restore from previous phone). Leave it alone.
3. Disconnect the phone. The home screen should pop up. Click on the Mail app. This is where it should have been crashing, but now you can see the logos (Yahoo, GMail, AOL, etc.). Click on one of the icons, then click cancel to get back to the home screen.
4. Plug in phone. See iTunes iPhone welcome screen again.
5. Click Restore.
6. Mail should work now.