Gmail, Yahoo and Outlook sender requirements: the rules for bulk and newsletter senders
Since February 2024, Gmail and Yahoo have required much more from senders than before, and since May 2025 Microsoft has followed suit for Outlook.com. If you don't meet the rules, you land in spam – or your emails are not accepted at all. Here's what applies to whom and how to check it.
Who do the rules apply to?
Google distinguishes two groups: all senders and bulk senders. You count as a bulk sender if you send around 5,000 or more emails a day to personal Gmail addresses. The count is per sender domain, even if the emails go out through different services. Once classified as a bulk sender, you stay one.
Yahoo coordinated with Google and has almost the same requirements. Microsoft uses the same threshold of 5,000 emails per day for Outlook.com, Hotmail and Live.com.
Even if you send far fewer than 5,000 emails a day: the bulk sender requirements are today's standard. Meeting them gives you better chances with every mailbox provider.
Requirements for all senders
- SPF or DKIM for the sender domain. Ideally both.
- A valid reverse DNS record (PTR) for the mail server's IP that points back to the same IP.
- Encrypted transport via TLS.
- A low complaint rate: below 0.3 %, better below 0.1 % (see below).
- Correctly formatted emails according to RFC 5322, for example with a valid date and Message-ID.
- No impersonation of other senders, in particular no forged @gmail.com senders.
Additional requirements for newsletters and bulk sending
| Requirement | What it means |
|---|---|
| SPF and DKIM | Both must pass, not just one. |
| DMARC record | A DMARC record for the sender domain is mandatory. p=none is formally sufficient. |
| DMARC alignment | The domain in the sender address (From) must match the domain of SPF or DKIM. A newsletter tool that signs with its own domain is not enough. |
| One-click unsubscribe | The List-Unsubscribe and List-Unsubscribe-Post headers according to RFC 8058, plus a visible unsubscribe link in the body. Unsubscribes must be processed within two days. |
Google has been enforcing the rules step by step since 2024: first came warnings and temporary errors, and now non-compliant emails are increasingly rejected rather than just filtered.
What Microsoft requires for Outlook.com
Since May 2025, similar requirements apply to bulk senders to Outlook.com, Hotmail.com and Live.com: SPF must pass, DKIM must pass, and there must be a DMARC record with at least p=none that aligns with SPF or DKIM. Microsoft initially moves non-compliant emails to the junk folder and has announced that it will reject them later. It also recommends a working unsubscribe option, valid sender and reply-to addresses and well-maintained lists.
One-click unsubscribe – how it works technically
For Gmail and Yahoo to show an “Unsubscribe” button right next to the sender, the email needs two headers:
List-Unsubscribe: <https://example.com/unsubscribe?id=8f2a…>, <mailto:unsubscribe@example.com> List-Unsubscribe-Post: List-Unsubscribe=One-Click
When someone clicks “Unsubscribe”, the mailbox provider sends a POST request to the https address. That address must process the unsubscribe without login and without further confirmation. Important: both headers must be covered by the DKIM signature. Common newsletter tools do this automatically – but check that the feature is turned on.
This requirement does not apply to transactional emails such as order confirmations or password links.
The complaint rate
The complaint rate is the share of recipients who mark your email as spam. Google names 0.3 % as the upper limit above which problems start; a good value is below 0.1 %. For 10,000 emails, 0.3 % is already 30 clicks on “Report spam”.
This value can only be measured by the mailbox providers themselves. For Gmail, there are the free Google Postmaster Tools, which show your domain reputation and complaint rate after a DNS verification. What helps: only email recipients who have opted in (double opt-in), regularly remove inactive addresses and make unsubscribing easy.
How to check where you stand
- Create a test address on the home page.
- Send your newsletter to this address exactly the way your recipients receive it.
- In the report you'll find the “Sender requirements” checklist with all of Gmail's, Yahoo's and Outlook.com's points – and instructions for every point that's missing.
No external test can measure the complaint rate; for that, the providers' postmaster tools remain the source.