Why are my business emails going to spam? How to fix it

Updated 10 November 2026 · by Mohamed, Growth with MK

You reply to a customer, send a quote or a newsletter, and hear nothing back. Then someone mentions they found you in their spam folder. If it keeps happening, especially with Gmail addresses, it's rarely bad luck. Gmail is telling you it can't be sure the email is really from you.

The short answer

Gmail decides where an email goes based mostly on two things: can it prove the email came from your domain (authentication), and do people want your email (reputation). Since February 2024, Google's sender guidelines require every sender to use SPF or DKIM. Anyone sending more than 5,000 emails a day to Gmail needs SPF, DKIM and DMARC, plus one-click unsubscribe on marketing email. Small senders aren't exempt from the filtering, though. Unauthenticated mail simply starts with less trust.

It's a common gap. Of 747 UK small-business domains we checked in November 2026, 46% had no DMARC record, 24% had no SPF record, and only about 10% were fully set up.

Common causes, most likely first

1. Missing or broken authentication. No SPF record, two SPF records (which breaks SPF), DKIM never switched on in your mailbox, or no DMARC record.
2. A tool sends "as" you without permission. Your booking system, shop, invoicing app or newsletter tool sends from your address, but your domain doesn't list it in SPF and it doesn't sign with your DKIM. You'll often see "via" and another company's domain next to your name in Gmail. That's a sign of this.
3. Sending from a free address. A gmail.com or hotmail.co.uk address used through another service can't pass DMARC for that address.
4. A sudden jump in volume. A brand-new domain or mailbox that suddenly sends hundreds of emails looks like a spammer.
5. People marking you as spam. Google asks senders to keep reported spam below 0.1% and never reach 0.3%. Mailing people who didn't ask to hear from you is the quickest way to get there.
6. Content and links. Link shorteners, links to sites with a poor reputation, image-only emails or a mismatch between the "from" name and the domain can all add risk. These matter less than the first five.

How to check

1. Run the free domain check on the domain after the @ in your email address.
2. Send a test to a Gmail address, open it, click the three dots → Show original. You want SPF: PASS, DKIM: PASS and DMARC: PASS.
3. If it did land in spam, open it. Gmail often shows a grey banner explaining why ("similar messages were used to steal people's personal information", "lots of messages from … were identified as spam").
4. Repeat for each tool that sends as you: shop, booking, invoices, newsletter.

How to fix it

1. SPF: one TXT record at your root domain starting v=spf1, listing your mailbox provider and every service that sends as you, ending ~all. Merge duplicates into one.
2. DKIM: switch it on in your mailbox (Google Workspace: Admin console → Apps → Google Workspace → Gmail → Authenticate email; Microsoft 365: Defender portal → Email authentication → DKIM; Zoho: Admin Console → Domains → DKIM). Then do the same in each sending tool. They'll give you CNAME or TXT records.
3. DMARC: add a TXT record at _dmarc: v=DMARC1; p=none; rua=mailto:you@yourdomain. Read the reports for two to four weeks, then move to p=quarantine.
4. Use your own domain for every customer-facing email.
5. Only email people who asked, and put a clear unsubscribe link on anything promotional.
6. Sign up to Google Postmaster Tools (free) if you send in volume. It shows your spam rate and authentication results for Gmail.

Customers on Outlook or Hotmail too? See emails going to junk in Outlook. Newsletters specifically? See Klaviyo and Mailchimp emails going to spam.

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• Klaviyo or Mailchimp emails going to spam? How to fix it
• Customers not receiving your invoices? Why invoice emails go to spam
• Contact form emails not arriving? Fixes for WordPress, Wix and Squarespace