A great email is wasted if it never reaches the inbox. Deliverability comes down to authentication, permission and engagement.
At a glance
- SPF, DKIM and DMARC are DNS-based checks that help mailbox providers confirm your emails are really from you.
- Gmail requires all senders to use SPF or DKIM; bulk senders also need DMARC.
- Gmail treats senders of roughly 5,000 or more messages a day to Gmail addresses as bulk senders.
- Bulk marketing emails need one-click unsubscribe, and Google asks senders to keep spam rates below 0.3%.
- Send only to people who asked to hear from you, and remove addresses that bounce.
Deliverability is whether your emails reach the inbox, rather than the spam folder or nowhere at all. Mailbox providers like Gmail decide based on whether they can verify your messages are genuine and whether recipients want them.
Authentication: proving your emails are yours
Three DNS-based standards help mailbox providers verify you:
| Standard | What it does |
|---|---|
| SPF (Sender Policy Framework) | Lists the servers allowed to send email for your domain |
| DKIM (DomainKeys Identified Mail) | Adds a digital signature showing the message wasn’t altered and came from your domain |
| DMARC | Tells receiving servers what to do if SPF or DKIM checks fail, and can send you reports |
You set these up by adding DNS records to your domain, usually with instructions from your email platform.
Gmail’s sender requirements
Google’s email sender guidelines apply to mail sent to personal Gmail accounts:
- All senders need SPF or DKIM authentication.
- Bulk senders, roughly 5,000 or more messages a day to Gmail accounts, need SPF, DKIM and DMARC. A DMARC policy of p=none is acceptable as a minimum.
- Bulk marketing messages must offer one-click unsubscribe, and unsubscribe requests should be honoured promptly.
- Google asks senders to keep their spam complaint rate below 0.3%, and recommends aiming for under 0.1%.
Google began applying these requirements in 2024 and has since tightened enforcement, so non-compliant mail may be rejected.
Careful
Sending to bought lists, old addresses or people who never signed up is the fastest way to high spam rates and bounces. Permission isn’t just a legal requirement under CASL; it’s the foundation of deliverability.
Engagement: show that people want your emails
- Send only to people who opted in. Our guide to building an email list explains how.
- Remove bounced addresses promptly.
- Make unsubscribing easy, so annoyed recipients unsubscribe instead of reporting spam.
- Send consistently, rather than long silences followed by sudden bursts.
- Re-engage or remove subscribers who haven’t opened in a long time.
Monitor and adjust
Google Postmaster Tools shows spam rates and authentication results for mail to Gmail users once you send enough volume. Your email platform’s reports on bounces, complaints and unsubscribes also show when something is wrong. Our guide to measuring marketing results covers which numbers to watch.
Questions readers ask
Do I need to set up SPF, DKIM and DMARC myself?
Usually you add DNS records provided by your email platform and domain host. Many email marketing services walk you through it. Your web host or IT support can help.
What does a DMARC policy of p=none mean?
It tells receiving servers to report on authentication results without rejecting or quarantining mail. Google accepts p=none as a minimum for bulk senders, and it’s a common starting point.
Why are my emails going to the Promotions tab?
Gmail sorts marketing emails into Promotions; that’s not the same as spam. Subscribers who want your emails will still find them there.
How can I check my spam rate?
Google offers Postmaster Tools, which shows data such as spam rates for mail sent to Gmail users from your domain once you have enough volume.
This guide is general information, not legal advice. Platform rules and CASL guidance change, so check Google’s documentation and the CRTC’s guidance before you rely on it.