mail application freeze

Hi everyone,

I am writing you with a very serious issue, which I encountered 2 months ago.

I have tried to send a large amount of data(20-30 mb) via my iPhone mail application ad since then it has been frozen. It doesn't start, even when I deactivate and re-activate my account. it doesn't start even with another account. It only shows a white screen with the icon for new mail, then crashes.

I have tried to reboot my device, close all applications, forced closing all applications(unlock button + central button), but nothing seems to be working.

Thank you in advance for your help