This is why I have started to really loathe GMail. I get that spam is a problem but, periodically, Google decides to shit-can e-mails from me to their subscribers with no notification to me or the recipient. I know for an absolute fact that no one sends spam from my server because I'm the only person who uses that server and it has no mail-sending scripts on it. My DKIM and SPF records are configured and working, my sending IPs have been consistent for years, and my domain's registration predates the existence of Google. But still, every 4 months or so, Google decides to get its hackles up for a few days and then everything goes back to normal.
0 - This is maybe one reason that compounds my frustration because I've been on the Internet long enough to remember when this wasn't a problem and when mail admins could talk to each other to resolve things like this.