When I delete email on my laptop, it does not delete on my cell phone or iPad and vice versa. Any advice on how to delete email once for all devices would be greatly appreciated.
You need to enable the account on all devices using the IMAP protocol instead of the POP3 protocol. Most email clients and mobile devices will now auto-configure them that way, especially since Comcast accounts are now IMAP compliant by default. So it sounds like at least one of your devices/computers is set up using POP3. If so you need to re-configure it using IMAP. If you need to manually configure the settings they are found here--------------------