You send a quotation, the client never replies, and a week later you learn it was sitting in their spam folder. Often the problem is not what you wrote but missing settings on your domain. Email services like Gmail and Outlook check three records to decide whether a message really comes from you.
SPF: who is allowed to send
SPF is a DNS record that lists the servers allowed to send email for your domain, for example your email provider and the service your website uses for contact forms. If a message comes from a server that is not on the list, it looks suspicious.
DKIM: a signature on every message
DKIM adds a digital signature to each email. The receiving server checks it against a public key published in your DNS. If the signature matches, the message was not changed on the way and really came from your domain.
DMARC: what to do when checks fail
DMARC tells receiving servers what to do with mail that fails SPF or DKIM: deliver it, send it to spam, or reject it. It can also send you reports, so you can see who is sending email in your name. Start with a monitoring policy, review the reports, then make it stricter.
Check yours in two minutes
- Send an email from your business address to a Gmail account.
- Open it in Gmail, click the three dots and choose "Show original".
- Look for SPF, DKIM and DMARC near the top. Each should say PASS.
If any of them says FAIL or is missing, that is the first thing to fix.
Other common causes
- Website forms that send mail straight from a shared hosting server, which may have a poor reputation. Use a proper email sending service instead.
- Several services sending for your domain, with only some of them listed in SPF.
- Sending to old or purchased lists, which leads to complaints and bounces.
These records take minutes to add once you know your setup, and the change usually shows within a day. It is one of the cheapest improvements a business can make.