Mail crashing on iPad pro

HI oscarbtt,

It sounds like the Mail app will work okay after you quit it and re launch it, but it playing up again pretty soon. There could be an issue with the account on the device, so what I would do is remove the account, or accounts if there are more than one and they use IMAP from the iPad first:

1. Tap Settings > Mail, Contacts, Calendars.
2. Tap the email account.
3. Tap Delete Account.

From: Get help with Mail on iPhone, iPad, and iPod touch

Then quit Mail, and Settings apps like you had before and restart the iPad. Once it is back on, add the account and test the issue again.

If that does not resolve it then I would next suggest backing up the device to iTunes and then restore it as new and verify that it works.

How to erase your iOS device and then set it up as a new device or restore it from backups
If it does, then restore your backup to either verify it still works and the software just needed reinstalled, or isolate the issue to the backup file itself. Thank you for using Apple Support Communities, give us an update when you've done that troubleshooting, if you would please!