If your quotes, invoices or replies keep landing in clients' spam folders, the problem is rarely what you wrote. In most cases, the receiving mail server simply can't confirm that the email really came from you.
Three DNS records do that job: SPF, DKIM and DMARC. If any of them is missing or wrong, Gmail, Outlook and other providers treat your mail with suspicion.
What SPF does
SPF (Sender Policy Framework) is a list of the servers allowed to send email for your domain. When a message arrives claiming to be from you, the receiving server checks whether it came from one of those approved servers.
A common mistake is having two SPF records, or forgetting to add a service you use, such as your CRM or invoicing software. Either one can cause genuine emails to fail.
What DKIM does
DKIM (DomainKeys Identified Mail) adds a digital signature to every email you send. The receiving server checks that signature against a public key published in your DNS. If it matches, the server knows the message wasn't altered on the way and really came from your domain.
Google Workspace and Microsoft 365 both support DKIM, but it often isn't switched on by default.
What DMARC does
DMARC tells receiving servers what to do when an email fails SPF or DKIM: deliver it anyway, send it to spam, or reject it. It also sends you reports showing who is sending email using your domain, including people trying to impersonate you.
Since 2024, Google and Yahoo have required DMARC for bulk senders, and many other providers now expect it from every business.
How to check your setup
- Look up your domain's SPF, DKIM and DMARC records with any free DNS checker.
- Make sure you have exactly one SPF record, and that it includes every service that sends email for you.
- Confirm DKIM is enabled in your email admin console.
- Start DMARC in monitoring mode, review the reports, then move to a stricter policy.
Other reasons email goes to spam
Even with all three records in place, email can still be filtered if you send from shared hosting servers with a poor reputation, send large volumes suddenly, or use subject lines and links that look like phishing.
The short version
Most spam-folder problems are fixable in an afternoon by someone who knows where to look. If you'd like us to check your domain, our free IT health check includes an email deliverability review.