Thank you both, it is as I suspected - there is no local storage of e-mails.

Our server does a purge and store of e-mails every morning a half hour after midnight and all viewed mail is stored on each users computer. Now I will have to set up some special mail server just for the eDGe that does a purge and store once a week, or get our programmer to produce an e-mail program for Android that has the option to have local storage - she isn't going to thank me for that idea.