Hello weepingbeech,
It sounds like what you are describing is a draft email or Mail windows.
To test this:
- Open Mail.
- Go to any mailbox.
- At the bottom left there should be two icons. One looks like two squares on top of each other. Press that. This link will provide a better look in the first image: Check your email in Mail on iPad
- If you swipe up. It will close anything open in another tab similar to how multitasking with apps work.
This feature is built-in to Mail and cannot be turned off. You can leave any feedback here: Product Feedback - Apple
If it is something else, let us know in detail what you mean be seeing.
Thanks.