Email Deliverability Basics: SPF, DKIM, DMARC and Inbox Placement

Email deliverability is whether your messages reach the inbox, rather than the spam folder or nowhere at all. You can write a brilliant campaign and still get poor results if it never arrives where people look. Many businesses only discover this when enquiries drop and nobody knows why.

Since 2024, Gmail and Yahoo have also published clearer requirements for senders, especially those sending in volume. The good news is that the foundations are not complicated. This guide explains what affects email deliverability, how to set up SPF, DKIM and DMARC, and what to monitor so you can find problems early.

What affects email deliverability

Inbox providers such as Gmail, Yahoo and Outlook want to protect their users. They decide where a message goes by looking at several signals together.

• Authentication: can the receiving server confirm that you are allowed to send for this domain?
• Reputation: the track record of your sending domain and the sending IP address.
• Recipient behaviour: do people open, click and reply, or mark messages as spam and delete without reading?
• List quality: bounces to addresses that do not exist and messages to spam traps hurt you.
• Content and technical setup: broken links, misleading text and badly formed email can add risk.

Most of these signals trace back to one question: did the recipient want this email? That is why consent and list quality, covered in our guide to email list building, come before any technical settings.

Authenticate your domain with SPF, DKIM and DMARC

These three DNS records prove that your emails really come from you. You add them in your domain's DNS settings, usually where you manage your domain or hosting. If you are not sure who controls your DNS, our guide to choosing website hosting explains the basics.

A sensible order of work

1. List every service that sends email as you. Your office mailbox, newsletter tool, website contact form, CRM, invoicing software and any shop platform.
2. Publish one SPF record that includes all of them.
3. Turn on DKIM in each service, using your own domain, and add the DNS records they give you.
4. Publish a DMARC record starting with a monitoring policy so you can see who is sending as your domain.
5. Read the reports, fix anything legitimate that fails, and only then consider a stricter policy.
6. Send test emails to a Gmail address and check the original message headers for passes on SPF, DKIM and DMARC.

Gmail and Yahoo sender requirements for bulk senders

In early 2024, Google and Yahoo began enforcing stronger rules for people sending large volumes of email. Google describes a bulk sender as one that sends close to 5,000 or more messages a day to Gmail addresses. Requirements and enforcement can change, so treat the following as a summary and read the current Google and Yahoo sender guidelines before you rely on it.

• Authenticate with SPF and DKIM, and publish a DMARC record for bulk sending.
• Make the domain in the visible From address align with your SPF or DKIM domain.
• Support easy unsubscribing for marketing and subscribed mail, including one-click unsubscribe through the List-Unsubscribe headers, and process requests promptly (the published guidance mentions within two days).
• Keep spam complaint rates low. Google's guidance has pointed to staying below 0.10% and avoiding 0.30% or more, as shown in Postmaster Tools.
• Have valid forward and reverse DNS for sending servers and use an encrypted (TLS) connection.

Even if you send far fewer than 5,000 emails a day, aim to meet these standards. Basic authentication is expected of all senders, and the habits protect you as you grow. Most modern email platforms set up one-click unsubscribe for you, but confirm it in your settings rather than assuming.

Use a recognisable sender and your own domain

Send from a real address on your own domain, with a consistent sender name such as "Priya at Green Valley School". Switching names and addresses every month confuses readers and reputation systems alike.

• Avoid sending bulk marketing from a free address such as a personal Gmail account. Authentication alignment with your own brand domain is a growing expectation.
• Use a reply-to address that a human actually reads. Replies are a positive signal.
• Consider a subdomain for bulk marketing, such as news.yourdomain.in, so a marketing problem does not affect day-to-day business email. This is a common practice, not a requirement.

Keep your list clean and your sending steady

Reputation is built slowly and lost quickly. Two habits protect it better than anything else.

Keep the list clean

• Email only people who agreed to hear from you, and never buy or scrape addresses.
• Remove hard bounces straight away.
• Stop sending to people who have not engaged for a long time, after one last re-permission email.
• Make unsubscribing obvious so unhappy people leave quietly instead of clicking "Report spam".

Send steadily

A new domain with no history that suddenly sends to thousands of people looks like a spammer. Start with your most engaged contacts, increase volume gradually over several weeks, and keep a regular schedule. This is often called warming up a domain. Your email platform may offer guidance on how fast to ramp up.

Write emails that look trustworthy

Content is rarely the only reason for spam placement, but careless emails raise the risk.

• Keep the subject line honest and matching the email. See our guide to email subject lines.
• Include real text, not just one large image.
• Use working links on your own domain where possible, and avoid link shorteners that hide the destination.
• Include your business name and postal address, and a visible unsubscribe link.
• Send a plain text version alongside the HTML version if your platform allows it.

Monitor your email deliverability

Do not wait for customers to say they never got your email. Check these regularly.

• Google Postmaster Tools: free tools that show domain reputation, spam rate and authentication results for mail sent to Gmail users, when your volume is high enough to produce data.
• Your email platform's reports: bounce rate, complaint rate, unsubscribes and clicks for each send.
• DMARC reports: they show who is sending mail using your domain, including any unknown or fraudulent sources.
• Seed tests: send to your own accounts at Gmail, Yahoo and Outlook and note where each message lands.

If problems appear, change one thing at a time: pause the affected segment, fix authentication, clean the list, then resume gradually. Our email marketing service includes a setup check, or you can contact us to have your records reviewed.

Frequently asked questions

Conclusion

Strong email deliverability comes from permission, authentication, a clean list, steady sending and regular monitoring. Get those right and your good content has a fair chance of being seen. If you want a second pair of eyes on your records, list and sending habits, see our email marketing service or talk to us.