LetterPop even saves your work as you go (though clicking the green save check mark from time-time isn't a bad idea). You can access your creations from your My Account page.
Those are the basics. Told you LetterPop is easy to use.
You can email your LetterPop links to as many people as you would like. And there are some big advantages to sending links instead of embedded HTML emails.
Want to make sure people can always read and reread what you create at LetterPop? Profiles allow you to archive as much as you want.