For example on my laptop with a trackpad for a mouse I was forever deleting things unexpectedly, and the mouse would do other weird things. I decided to disable the trackpad and move to a normal mouse, and that solved my problem.
I can't see what make or model computer you're using, nor what software you use to manage your emails, so all I could suggest is, if it is a laptop, stop using the trackpad.
Sometimes, when I'm writing an e-mail, I, inadvertently, hit a key that wipes out the e-mail. It isn't saved in drafts and I can't get it back no matter what I do.. What key do I hit that causes this? it's, especially, worrisome when I'm 90% through a long e-mail. I thank you, beforehand, for any answer that will solve this for me.