Email or gmail? If you have/create a folder called saved in gmail in your computer, you can change labels in the app, or you can simply "archive" an email. It will go out of sight, but be saved. I'm sure the email app has a similar function, but I only use gmail these days.
thanks - but I'm using email, not gmail - and there does not appear to be a away to create additional mail folders or save messages - seems very strange to omit such a basic function.
Try another email app. Folder support may depend on your email account as well. I can't say for certain as I don't use the stock email app and I'm on Exchange so things are a bit different for me.