Gmail and Yahoo bulk sender rules: a practical checklist

In 2024 Gmail and Yahoo introduced firm requirements for anyone who sends email in volume. Microsoft followed with similar rules for Outlook.com addresses in 2025. If your newsletters suddenly land in spam, there is a good chance one of these items is missing.

Who counts as a bulk sender

Gmail treats a sender who sends around 5,000 or more messages a day to Gmail addresses as a bulk sender. Yahoo uses its own volume criteria. In practice, follow these rules at any volume: they are simply good practice, and small senders benefit too.

The checklist

1. Authenticate with SPF and DKIM

SPF lists the servers allowed to send for your domain. DKIM adds a cryptographic signature to each message. Bulk senders need both, set up on the domain in your From address.

2. Publish a DMARC record

DMARC tells mailbox providers what to do when SPF or DKIM fail, and it requires that the authenticated domain aligns with the From domain. Google's guidelines accept a policy of p=none to start, but you must have a record.

3. Offer one-click unsubscribe

Marketing and promotional mail needs a one-click unsubscribe in the message headers, following the standard known as RFC 8058. The opt-out must be honoured within two days. A link at the bottom of the email is still a good idea, but it is not a substitute for the header.

4. Keep spam complaints under 0.3%

The hard ceiling is a 0.3% spam complaint rate, and the target is under 0.1%. That means fewer than 1 complaint per 1,000 delivered emails. Complaints rise when people did not expect your mail, cannot find how to leave, or receive it too often.

5. Get the basics right

Your sending servers need valid forward and reverse DNS, and messages must follow formatting standards. A good SMTP provider takes care of this for you.

A simple order of work

Add SPF and DKIM for your sending domain at your DNS provider.
Add a DMARC record with p=none and a reporting address, then read the reports for a few weeks.
Confirm your platform adds List-Unsubscribe and List-Unsubscribe-Post headers.
Remove addresses that bounce and people who have not engaged in a long time.
Move DMARC to quarantine or reject once all your legitimate mail passes.

How SG Reach helps

The Domains page in SG Reach shows the SPF, DKIM and DMARC records to add and checks them live. Every campaign is DKIM signed, includes one-click unsubscribe headers, and respects a suppression list that is updated automatically from bounces, complaints and unsubscribes.