SPF, DKIM and DMARC all passed. Gmail still sent my mail to spam.

Ask anyone why their email is going to spam and the first answer is always the same: check SPF, DKIM and DMARC. It's good advice. It's also where most guides stop.

In August 2026, mail from my own domain (I'll call it mydomain.example here) was going to Gmail's spam folder no matter how I sent it. All three checks passed. No blocklist had the domain. It stayed in spam anyway.

It's back in the inbox now. This is what I measured, what I found, and what I think got it out.

How bad it was

This is the address I've used with my readers for years. Up to the end of 2024, about half of what I sent from it got opened. I sent almost nothing through 2025, came back in December with a few thousand promotional emails in a row, and in April 2026 moved the domain's mail to Google Workspace.

By May, opens from Gmail users were at 5.9%. By August, 0.2%.

What told me it wasn't the content: I sent the same message to the same 1,783 people from a different address I own, in the same week. 30.7% of them opened it. Only the sender had changed.

What I ruled out

I sent a two word plain text test to a Gmail account four ways: directly from Workspace, through SocketLabs, through my old host's mail server, and through the Gmail API. All four went to spam, and all four passed authentication. So it wasn't the route. The domain itself had a bad name.

I took out every tracking link in case one looked like a trap. Still spam.

Google Postmaster Tools showed nothing, which I first took as good news. It isn't. For a domain that sends as little as mine, Google simply doesn't show the data.

What I actually found

When I moved the mail to Workspace, one thing didn't move with it. A warm-up service I'd connected months earlier was still attached to the old mail server, still sending about 40 emails a day from my address. The receiving half of that warm-up had nowhere to work anymore, because incoming mail now went to Google.

The two things I changed

On August 21st I switched the warm-up off and reconnected everything to Google.

On August 22nd I launched a small birthday giveaway for my readers, set up so that signing up sent you a confirmation email from that address, and your entry only counted once you replied to it. The announcement warned it might land in spam and asked people to look. The next day, a reminder went out from my other address to everyone who hadn't replied.

So real people went into their spam folders, found my mail, and wrote back.

What happened

I had a test going to a Gmail account every morning, reading back whether it landed in spam or the inbox. It said spam every day through August 31st. On September 1st it said inbox, and it has stayed there.

I can't tell you which change did it. They were a day apart. My guess is the replies, but I didn't set it up cleanly enough to prove it.

If you're here because your mail is in spam

Don't read an empty Postmaster Tools page as healthy. And if you've moved your domain's mail anywhere in the last year, go looking for anything still attached to the old server. That's what I missed for four months.