we want to the message composer to be able to choose whether to save automatically or not.

The message composer has auto-save enabled, but we would like to be able to select settings that are not automatically saved.

if it has been modified but not saved, we want to be display pop-up "leave the page? you have not save the email." like a traditional editor.

Why we need this feature:

Some users just confirm the email content. If the user inadvertently make changes by operating the keyboard or mouse, the changes will be saved without being noticed, it to an accident.

Also, even though the user just opened it to check the contents of the email, it is auto-saved and the last update time will change. Other users are worried if the content of the email has been updated because the last update time will change. It is very confusing to be saved just by browsing.