Originally Posted by Crashdamage
Not so at all.
It's not a matter of an app, it's just the way POP3 email works. No doubt you have Outlook set to delete mail on the server and your Android mail client to sync deletes. If you want mail to stay on your phone set Outlook to leave mail on the server.
On the phone it seems to initially just collect the email title and who its from. Doesn't download the actual message to your phone. If you want to read an email which is listed on your phone but at the time you have no network connection it just says loading.... and the message isn't there to read.