But I need to keep them on my computer. Or, are you saying that, once they've been downloaded to the Powerbook G4 and iPhone 4, if I delete them on webmail, they'll disappear from my iPhone?
I think my experience has been that, if I delete my road runner webmail emails, it has no effect on e mail already downloaded to my MPB or iPhone 5s.
I read a nifty-sounding 'trick' for deleting piles of email on an iPhone, but the tipper said not to try it on massive amounts or it would freeze up the iPhone. You check the top email (which activates the 'Move' button so it becomes clickable). Then holding the Move button, unclick the top email and wait, holding down 'Move' (while, seemingly, nothing's happening). Once all the email has been moved, you are presented with a screen with the option to move the moved mail to trash. I'll attach a screenshot of that screen, showing what happened just now to all the (16) emails presently on this iPhone 5s...
