I have 3 computers and an iPhone, each of which gets my comcast emails. I have to delete them on each device separately. Is there a way to delete my mail once?
No. That requires an IMAP server, which can synchronize email between devices, but Comcast currently only provies POP.
The closest option is to configure all the computers to remove messages from the server after downloading. Then the other devices won't download the messages at all if they've been downloaded to another device, so you won't need to delete them.
