This is why I never use Gmail. All the spam filters in the world won't stop other people's emails from reaching me. (Oh, and Google's spam filters are pretty bad: they routinely route messages to the spam folder, even when they come from addresses I've corresponded with. It may be a DKIM/DMARC/SPF issue, but you would think that an incoming response to an email I sent would have a low spam score, even if the sender's mail server isn't configured 100% perfectly.)