This is really frustrating along with them removing POP for external accounts. I have an old email account that I had configured to have my Gmail account pull in emails from, and I can reply from that email using this feature, and now their only suggestion is to set up forwarding on the old email account to Gmail but that is way less reliable, and even then I wouldn't be able to reply. It's confusing because like, I'd figure they'd want more data, not less.