Glossary
Bulk sender requirements
Also called Google and Yahoo sender requirements, Outlook.com sender requirements, February 2024 email requirements.
Last reviewed 11 October 2026
What are the bulk sender requirements?
The bulk sender requirements are the rules Google and Yahoo have enforced since February 2024, and Outlook.com since May 2025, on high-volume senders: SPF and DKIM both passing, DMARC aligned with the From domain, and, at Google and Yahoo, one-click unsubscribe and a spam complaint rate under 0.3 per cent.
Google counts a sender as bulk from close to 5,000 messages a day to personal Gmail accounts from one domain, and Microsoft from over 5,000 a day to Outlook.com, Hotmail.com and Live.com addresses; Google and Yahoo also ask that an unsubscribe be honoured within two days. Below the bulk line Google still asks every sender for SPF or DKIM, and mail with neither may be marked as spam or rejected with a 5.7.26 error. Microsoft says bulk mail to Outlook.com that misses its requirements is rejected with a 550 5.7.515 error.
The practical reading for a small sender is that the whole list applies anyway. You will cross the bulk line on a good month, none of it is work worth doing reactively, and between them these providers hold most of the consumer addresses an English-language course is sent to.
See also
- Spam complaint rate
A spam complaint rate is the count of people who pressed the spam or junk button divided by the mail delivered to that provider over a window it chooses, and both Google and Yahoo name 0.3 per cent as the level to stay under, with Google naming 0.1 per cent as the level to aim at.
- One-click unsubscribe
One-click unsubscribe is a mail client operating the unsubscribe on the reader’s behalf by POSTing to an https URI the sender put in the message headers, with no browser, no confirmation page and no further interaction from the reader, as RFC 8058 defines it.
- DMARC
DMARC is the DNS policy that ties SPF and DKIM to the domain a reader actually sees, telling receivers what to do with mail from your domain that aligns with neither and asking for aggregate reports about it, and it is defined in RFC 7489.
- Deliverability
Deliverability is the share of the mail you send that reaches the inbox of the person you addressed it to, as distinct from delivery, which is only the share the receiving server accepted rather than bounced.
Read next
This term is covered properly in Email deliverability for small senders: what decides it, which is a longer piece on the subject.
Every other term is on the glossary index , the longer writing is in the guides, and what this site itself does is on the home page.
Thinking of writing an email course?
5dayemail hosts a five-to-ten day email course: you write it once, and everyone who joins your list gets one email a day, in order, starting from the day they confirm.
Sign in with Google and your account opens on the Free plan. There is no card to enter, and nothing is charged unless you choose the paid plan.