mail Won't Open Just Flash Then Close

I resolved a similar problem! I had tried:

• restarting device
• updating iOS
• deleting and re-adding the account
• deleting the the account and adding a different account
• deleting account and not adding any

Nothing changed the behavior until I closed everything, turned on airplane mode and opened the mail app with no WiFi connection. It showed me a draft that was started which had a photo attached. I deleted the draft and then turned off airplane mode and the mailbox showed up again.