In February 2024 Google and Yahoo introduced stricter rules for senders and have enforced them more strictly since. Mail that doesn't comply gets deferred, lands in spam or is rejected. Microsoft introduced comparable rules for bulk senders to Outlook.com in 2025. Here is what applies – and to whom.
For all senders
- SPF or DKIM for the sending domain.
- Valid forward and reverse DNS: the sending IP needs a PTR record whose hostname resolves back to that IP.
- TLS for transmission.
- Spam rate below 0.3% as measured in Google Postmaster Tools; staying below 0.1% is recommended.
- Well-formed messages per RFC 5322, without impersonating senders such as
@gmail.comin the From field.
Additionally for bulk senders
Google considers you a bulk sender if you send close to 5,000 or more messages to Gmail accounts in a day. The classification sticks even if your volume later drops. Then also:
- SPF and DKIM – both, not just one.
- A DMARC record for the sending domain, at least
p=none. - Alignment: the From domain must match the SPF or DKIM domain.
- One-click unsubscribe for marketing mail via
List-UnsubscribeandList-Unsubscribe-Post: List-Unsubscribe=One-Click(RFC 8058), plus a visible unsubscribe link in the body. - Honor unsubscribes within two days.
What the spam rate really means
It counts users who mark a message as spam relative to messages delivered to the inbox. 0.3% is three complaints per thousand delivered emails – a line a single poorly maintained list can cross. The usual causes:
- Recipients don't remember signing up – no double opt-in or long gaps between sends.
- The unsubscribe link is hidden or broken, so “spam” is the easiest way out.
- The emails don't match what was promised at signup.
What to do now
- Set up SPF, DKIM and DMARC for your sending domain (see the guide).
- Add your domain to Google Postmaster Tools and watch the spam rate.
- Enable one-click unsubscribe for all newsletters.
- Separate transactional email from newsletters – ideally by IP or subdomain.
- Remove inactive recipients regularly.
With ridu: SPF, DKIM and DMARC alignment come from two DNS records; sending IPs have matching reverse DNS and use TLS. Broadcasts get the one-click headers automatically and unsubscribes take effect immediately. The dashboard shows bounce and complaint rates against the providers' limits, and every email carries a
Feedback-ID for Postmaster Tools.