If this is on a POP3 account, you must read it on the Mac to appear as read. If it is an IMAP account, then it is an IMAP settings problem. However, the way you discribe it, it sound like POP3.
If this is on a POP3 account, you must read it on the Mac to appear as read. If it is an IMAP account, then it is an IMAP settings problem. However, the way you discribe it, it sound like POP3.