HubSpot email deliverability: meet Gmail, Yahoo and Microsoft rules
What Gmail, Yahoo and Outlook.com require from bulk senders in 2026, and how to set up SPF, DKIM, DMARC and unsubscribes correctly in HubSpot.
If you send marketing email from HubSpot to a few thousand people a day, Gmail, Yahoo and Microsoft's Outlook.com all expect the same basics: authenticate your sending domain with SPF, DKIM and DMARC, make unsubscribing quick and easy, and keep spam complaints low. In HubSpot, most of this comes down to connecting your email sending domain properly and checking a few DNS records.
Enforcement has tightened. Google says that from November 2025 Gmail has been ramping up enforcement on non-compliant traffic, including temporary and permanent rejections, and Microsoft's rules for high-volume senders to Outlook.com took effect on 5 May 2025. Here is what each provider asks for at the time of writing (November 2026), and how to check your HubSpot setup.
What the three providers require
| Requirement | Gmail (bulk senders) | Yahoo (bulk senders) | Outlook.com (high volume) |
|---|---|---|---|
| Who it applies to | Close to 5,000 or more messages a day to personal Gmail accounts | Bulk senders to Yahoo users | More than 5,000 emails a day to Microsoft consumer accounts |
| SPF and DKIM | Both | Both | Both must pass |
| DMARC | Required, p=none accepted, aligned with SPF or DKIM | Required, at least p=none, aligned | Required, at least p=none, aligned |
| One-click unsubscribe | Required for marketing and subscribed messages | Required for marketing and subscribed messages | Not part of the authentication rule |
| Honour unsubscribes | Within 48 hours | Within 2 days | Not part of the authentication rule |
| Spam complaint rate | Below 0.3%, ideally below 0.1% | Below 0.3% | Not part of the authentication rule |
A few details matter:
- Gmail bulk sender status is permanent. Google says senders who meet the threshold even once are permanently treated as bulk senders, and messages from the same primary domain are counted together.
- Gmail's rules apply to personal Gmail accounts, not Google Workspace recipients. Most B2B lists still contain plenty of personal addresses, so plan as if the rules apply to you.
- All senders to Gmail and Yahoo need at least SPF or DKIM and a spam rate below 0.3%, whatever their volume.
- Microsoft says non-compliant mail is sent to junk, and may be rejected with the error "550 5.7.515 Access denied" if the issues aren't fixed.
Connect your sending domain in HubSpot
HubSpot recommends connecting your email sending domain so your marketing emails are authenticated. If you don't, HubSpot sends through a HubSpot-managed domain instead, which it says may affect engagement. The setup involves these DNS records:
- DKIM: two CNAME records. HubSpot requires DKIM before you can send with your own domain in the From address.
- SPF: HubSpot already handles SPF for marketing email on its shared servers, but recommends adding its SPF TXT record to your From address domain. Accounts with a dedicated IP need SPF on their return path domain.
- DMARC: HubSpot doesn't strictly require it to send, but notes that Google and Yahoo require DMARC, DKIM and SPF for bulk senders and that non-compliant mail will bounce. HubSpot Support can't set DMARC up for you, so it sits with your IT team, DNS provider or a DMARC service.
-
MX: HubSpot recommends removing a null MX record (
MX 0 .) from sending domains, because some providers reject mail from domains that have one.
On SPF, a domain should publish only one SPF record, and the SPF standard limits the number of DNS lookups a record can trigger to ten. Add HubSpot to your existing record rather than creating a second one, and remove services you no longer use.
Set up DMARC and alignment
Start with a monitoring policy, for example v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com, which all three providers accept as a minimum. The rua address receives aggregate reports showing which services send email using your domain, and Yahoo strongly recommends including it.
Alignment means the domain in your visible From address matches the domain that passed SPF or DKIM. When your sending domain is connected, HubSpot signs your email with DKIM for your own domain, which is what lets DMARC pass through DKIM alignment.
Once the reports show every legitimate sender passing (HubSpot, your office mailboxes, billing and support tools), you can consider moving to p=quarantine and later p=reject. Microsoft's postmaster guidance recommends reject, while Gmail and Yahoo accept none. Move in stages, because a strict policy also blocks any legitimate service you forgot to authenticate.
Unsubscribes and spam complaints
Gmail and Yahoo require one-click unsubscribe on marketing messages, using the List-Unsubscribe and List-Unsubscribe-Post headers described in RFC 8058, plus a clearly visible unsubscribe link in the email body. Rather than assume your setup is compliant, send a HubSpot marketing email to a Gmail address, open Show original, and confirm both headers are present. Do the same for one-to-one sales emails sent through a connected inbox, as these travel by a different route.
Spam complaints are the other half of the picture:
- Register your domain in Google Postmaster Tools and watch the user-reported spam rate. Google advises staying below 0.1% and never reaching 0.3%.
- Email people who opted in, and stop sending to contacts who haven't engaged in a long time.
- Use email frequency caps. Since August 2026, Marketing Hub Professional and above can set caps per brand, so one brand's audience isn't over-emailed.
- Keep the sender name and subject lines recognisable, so people unsubscribe instead of reporting spam.
Authentication gets you through the door. Low complaint rates keep you in the inbox.
A 30-minute deliverability check
- 1 In HubSpot, confirm your email sending domain is connected and the DKIM records are verified.
- 2 Look up your domain's SPF record: one record only, covering HubSpot and every other service that sends as you, within the ten-lookup limit.
-
3
Look up
_dmarc.yourdomain.comand confirm a DMARC record exists with at leastp=none. - 4 Check there is no null MX record on the sending domain.
- 5 Send a test marketing email to Gmail and Outlook.com addresses and check the headers for SPF, DKIM and DMARC passes and the unsubscribe headers.
- 6 Review your spam rate in Google Postmaster Tools every week or two.
This article is general technical information, not legal advice on email marketing law or consent.
Frequently asked questions
Do these rules apply if we send fewer than 5,000 emails a day?
Some do. Gmail and Yahoo require all senders to use at least SPF or DKIM and keep spam rates below 0.3%. Setting up SPF, DKIM and DMARC anyway is good practice, and Gmail's bulk status is permanent once you cross the threshold.
Can HubSpot set up DMARC for us?
No. HubSpot's documentation says Support can't help with DMARC setup. It is configured in your domain's DNS by your IT team, DNS provider or a DMARC service.
Why do emails show as delivered in HubSpot but never arrive?
HubSpot notes that quarantined emails can show as delivered in HubSpot while never reaching the recipient. Missing or failing authentication is a common cause, so check your DKIM, SPF and DMARC results first.
Need help with your HubSpot email setup?
We connect sending domains, review DNS records and tidy email settings as part of our HubSpot services. If your HubSpot website needs attention too, our HubSpot CMS website development guide covers the build side. Talk to us about a deliverability check.
Sources: Google: email sender guidelines, Google: sender guidelines FAQ, Yahoo: sender best practices, Microsoft: Outlook.com postmaster policies, Microsoft: fix NDR error 550 5.7.515, HubSpot: overview of email authentication, RFC 8058, RFC 7208 (SPF), HubSpot August 2026 product updates
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