On October 3, 2023, Google and Yahoo jointly announced new requirements for anyone sending more than 5,000 emails per day to their users. The deadline is February 2024. Most B2B outbound teams do not send "bulk email" in the marketing sense, but the rules apply to anyone running multi-inbox sequences at scale, and the enforcement will ripple down to smaller senders fast. Here is the plain-English version.

The three rules in plain language

  1. Authenticate your email properly. SPF, DKIM, and DMARC must all be configured on every sending domain. No exceptions.
  2. Stay under a 0.3% spam complaint rate. Google specifically called out 0.1% as the healthy target and 0.3% as the ceiling.
  3. Make unsubscribe one-click. The List-Unsubscribe header must be present, and the unsubscribe action must work in a single click.

What this actually means for cold outreach

Cold email was already supposed to do all of this. In practice, a lot of teams got away with half-measures for years. After February 2024, half-measures will get your domain silently suppressed — not bounced, not flagged, just not delivered. That's the scary part: you won't see it happen.

The checklist

SPF

Every sending domain needs an SPF record that authorizes your sending infrastructure. If you use Google Workspace plus a sequencer, both need to be in the record. Missing this is the #1 cause of silent deliverability death.

DKIM

Each mailbox provider you send through must have its DKIM key published on your domain. Google's key alone is not enough if your sequencer signs messages separately.

DMARC

Minimum is p=none with a reporting address. Better is p=quarantine. Best is p=reject once you're confident your SPF and DKIM are clean. p=none is compliant for the new rules, but it's also the weakest posture.

List-Unsubscribe header

Most modern sequencers add this automatically. Check yours. The header must be present and the unsubscribe must work on one click without a login.

Complaint rate monitoring

Sign up for Google Postmaster Tools for every sending domain. This is the only way to see your actual complaint rate from Gmail's perspective.

What changes for multi-inbox senders

If you run 10 sending domains, you now have 10 times the SPF/DKIM/DMARC setup work and 10 times the monitoring. Teams running heavy outbound volume will need to automate this — manually tracking 10 Postmaster accounts is a recipe for missing a problem until it's too late.

"We went from 'deliverability is mostly fine' to 'deliverability is a full-time job' in one announcement. And that's probably how it should have been all along."

What to do this month

  1. List every domain you send cold email from.
  2. Run each one through mxtoolbox.com for SPF, DKIM, DMARC.
  3. Enroll every domain in Google Postmaster.
  4. Verify your sequencer adds the List-Unsubscribe header.
  5. Run a test send from each inbox to mail-tester.com — aim for 10/10.

Do this before December 2023 and you'll enter February with no surprises. Ignore it and expect a mysterious drop in reply rates starting Q1 2024.