iPhone glitching when I am writing an email message

After the latest update, I've been experiencing an issue when I am drafting an email message.

When I'm in the midst of drafting a message, the phone will suddenly throw me out of the mail application, and I have to open the application back up to restart the message over and over until I can get pass the glitch and then send the message. The problem thus far appears to be erratic and only occurs when I use the Mail application on my phone.

I've tried shutting my phone off completely for brief periods of time but the glitching still continues and is starting to increase in frequency. What do you advise?

Thank you!