See the followng Xamarin.Essentials: Email for the very basics. Note the tabs for different OS. Other option is creating a web app setup for responsive design using BootStrap 5.
How to make simple email client application?

Himanshu Acharya (CS)
1
Reputation point
Hello,
I am guidance to make a simple not complex (like outlook and thunderbird) email client application (like outlook and thunderbird) which will work on all platforms(windows, Mac, Linux, iOS and Android) . Please help me