Mail Health Report

Why are my emails going to spam?

Inboxes decide where a message goes in two stages. First they check whether it really came from you. Then they judge whether people want it. Most business email that lands in spam fails the first stage, and that part is fixable in DNS, often in minutes.

Last reviewed 17 October 2026

Stage 1: can the inbox prove the email is from you?

Gmail, Yahoo, Outlook.com and corporate filters check three DNS records before anything else. If they’re missing or broken, your email looks no different from a fake one using your domain.

  • No SPF record, or a broken one. SPF lists the services allowed to send email on your behalf. Two SPF records, or more than 10 DNS lookups, make it fail completely. Check your SPF record.
  • Email isn’t signed with DKIM. DKIM adds a digital signature that proves the message wasn’t altered and came from your domain. Many providers need you to switch it on. Check for DKIM keys.
  • No DMARC record. Gmail, Yahoo and Microsoft now expect one from anyone sending in volume, and many filters treat domains without it with more suspicion. Check your DMARC policy.
  • A sending service that passes SPF but fails DMARC. Newsletter tools, CRMs and invoicing systems often send “on behalf of” their own domain. The message authenticates, but not as you, so DMARC fails. How to fix a sending service.
  • A mail server without reverse DNS. If you run your own server or send from a website, its IP address should point back to a proper host name. Gmail requires this from all senders.

The quickest way to see all of these at once is the free email health check. It reads your public records and lists what to fix first.

Stage 2: do people want your email?

Once a message is proven genuine, filters weigh your sending history and how recipients react.

  • Spam complaints. Gmail asks bulk senders to keep complaints below 0.3% of messages, and ideally below 0.1%. A few people clicking “Report spam” on a newsletter can push you over.
  • No easy way to unsubscribe. Marketing email must include a one-click unsubscribe link. People who can’t leave a list mark it as spam instead.
  • Sudden jumps in volume. A new domain or IP address that suddenly sends thousands of messages looks like a spammer. Increase volume gradually.
  • Bought or old lists. Addresses that bounce, or spam traps hidden in old lists, damage your reputation quickly.
  • Blocklists. If your sending IP address or domain appears on a public blocklist, many filters will junk or refuse your email. Your email provider can tell you whether its servers are listed.
  • Content and links. Shortened links, links to domains with a poor reputation, a single large image with little text, or attachments people don’t expect can all count against a message.

How to find the cause of one message

  1. Ask the recipient to open the message in their spam folder and copy its headers (the technical details hidden at the top).
  2. Paste them into the email header analyser. It shows whether SPF, DKIM and DMARC passed, for which domain, and any spam scores the receiving server added.
  3. If authentication failed, fix the records the analyser points to. If everything passed, the cause is reputation or content, so look at Stage 2.

Free tools from the inbox providers

If you send a lot of email to Gmail addresses, Google Postmaster Tools shows your domain’s spam rate and reputation as Google sees it. Microsoft’s Smart Network Data Services (SNDS) gives similar information for IP addresses sending to Outlook.com. Both are free and need you to prove you own the domain or IP address.

For the rules the big providers now enforce, read Gmail, Yahoo and Microsoft sender requirements. For how the three records work together, see SPF, DKIM and DMARC explained.

Why do my emails go to spam in Gmail but not Outlook?

Each provider runs its own filters and keeps its own view of your reputation. Gmail is strict about authentication and complaint rates, so a missing DMARC record or an unauthenticated sending service often shows up there first.

Will setting up SPF, DKIM and DMARC stop all my email going to spam?

It removes the most common cause and is required by the major providers, but it doesn’t guarantee the inbox. Reputation, complaints and content still count once your email is proven genuine.

Why do emails from my website contact form go to spam?

Website forms often send from the web server itself, which isn’t in your SPF record and doesn’t sign with your DKIM key. Send form email through your email provider or a sending service you’ve authenticated for your domain.

How long does it take to fix?

DNS changes usually take effect within an hour. Rebuilding a damaged reputation takes longer, typically several weeks of steady sending to people who want your email.