The Gmail, Yahoo and Outlook sender rules, explained simply

The big inbox providers now have clear rules for anyone sending marketing email. Here is what they require, who they apply to and how to check you comply.

Updated June 3, 2025Published February 6, 20243 min read

For years, the rules for getting into the inbox were unwritten. Not any more. Gmail and Yahoo set out clear requirements for senders in February 2024, and Microsoft followed for Outlook.com, Hotmail and Live addresses in May 2025.

If you send newsletters or marketing emails, these rules affect you. The good news is that most email marketing tools make them easy to meet, once you know what to look for.

Who the rules apply to

Some rules apply to everyone who sends email to these providers. Stricter rules apply to bulk senders, which roughly means anyone who sends around 5,000 or more emails a day to that provider's users.

Even if you are smaller than that, follow all of the rules anyway. They are good practice, they improve your chances of reaching the inbox and your list may grow into the bulk range sooner than you think. Google has also said that once you count as a bulk sender, you stay counted as one.

Rule 1: Authenticate your emails

You need to prove your emails really come from you. That means setting up three records on your domain:

  • SPF: lists the services allowed to send email for your domain.
  • DKIM: adds a digital signature to each email so it cannot be changed or faked.
  • DMARC: tells inbox providers what to do with emails that fail those checks.

For bulk senders, all three are required. At minimum, DMARC must exist with a policy of none, which looks like this:

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

The email in your "from" address also needs to align with these checks. In plain words, the domain people see in the from address must match the domain that passed SPF or DKIM. Authenticating your own domain inside your email tool usually takes care of this.

Microsoft now applies these same checks to bulk senders. Emails that fail can be sent to junk or rejected outright.

Rule 2: Keep spam complaints low

Every time someone clicks "report spam", it counts against you. Gmail and Yahoo want your spam complaint rate below 0.3 percent, and recommend keeping it under 0.1 percent. That is fewer than one complaint for every thousand emails.

If you send to Gmail users often, Google Postmaster Tools shows you your spam rate for free.

Rule 3: Make unsubscribing easy

Marketing emails must include a clear unsubscribe link. Bulk senders must also support one click unsubscribe, a hidden setting in the email that lets inbox apps show their own unsubscribe button. Requests should be honoured quickly, within two days.

Reputable email marketing tools add one click unsubscribe automatically. If you send from your own system, your developer will need to add the List-Unsubscribe headers.

Rule 4: Use a proper technical setup

These points are mostly handled by your email tool or server, but they are worth knowing:

  • Send over a secure connection, known as TLS.
  • Your sending servers need valid reverse DNS, which links an IP address back to a domain name.
  • Format your emails according to email standards.

If you use a well known email marketing tool, these are already in place.

Rule 5: Do not pretend to be someone else

Never send from an address on a domain you do not control, such as a gmail.com or yahoo.com address through an email marketing tool. This is exactly the kind of thing these rules are designed to stop, and many tools no longer allow it.

A quick checklist

  • Your sending domain is authenticated in your email tool.
  • SPF, DKIM and DMARC records all exist and pass.
  • Your from address uses your own domain.
  • Every marketing email has a working unsubscribe link.
  • Your spam complaint rate is below 0.1 percent.

To test, send an email to a Gmail account, open it, and choose "Show original" from the menu. You should see PASS next to SPF, DKIM and DMARC.

Why this is good news

These rules can feel like extra work, but they mostly punish spammers and people who fake other brands. If you email people who asked to hear from you and set up your domain properly, the rules work in your favour. The inbox becomes a little less crowded, and your emails stand out.

Mailbox providers update their filters and requirements regularly. This guide was last reviewed on June 3, 2025. Spotted something out of date? Tell us.