Why Are My Emails Going to Spam? 10 Causes and Fixes

Most emails go to spam for one of three reasons. The first is failed authentication: SPF, DKIM or DMARC is missing or misaligned. The second is a weak sender reputation, which comes from a new domain, spam complaints or a blocklisted IP. The third is content that looks like spam. Check authentication first, because it is the most common cause and the quickest to fix.

How to diagnose before you change anything

Don't guess. Send a test message from your business address to a personal Gmail or Outlook.com account, open it, and view the original message ("Show original" in Gmail, "View message source" elsewhere). Find the Authentication-Results header:

Authentication-Results: mx.google.com;
  dkim=pass header.d=example.com;
  spf=pass smtp.mailfrom=example.com;
  dmarc=pass (p=QUARANTINE) header.from=example.com

Three passes for your own domain means authentication is fine, so look at reputation and content. Any fail, softfail, none or neutral result is your first fix. If you send in volume to Gmail users, Google Postmaster Tools adds data on domain reputation and spam rate.

Authentication problems

These are the most common causes, and the fastest to fix.

1. SPF is missing, wrong or over the lookup limit

SPF lists the servers allowed to send for your domain. Common mistakes:

No SPF record, or two SPF records. Only one v=spf1 TXT record is allowed, so merge them.
A sending service is missing, such as your newsletter tool, CRM or invoicing app.
More than 10 DNS lookups. Every include:, a, mx and redirect counts towards the limit. Going over it causes a permerror, which receivers treat as a fail.

Fix it with one clean record that includes every legitimate sender. Step by step: how to set up an SPF record.

2. DKIM isn't signing your mail

DKIM adds a cryptographic signature that proves the message wasn't changed and was authorised by your domain. If your provider's DKIM record was never published, or a third-party tool signs with its own domain instead of yours, receivers see no valid signature for you. See how to set up DKIM.

3. No DMARC, or DMARC alignment fails

Since 2024, Gmail and Yahoo require bulk senders (roughly 5,000+ messages a day to their users) to have SPF, DKIM and a DMARC record. Bulk mail must also offer one-click unsubscribe and keep spam complaints low. Smaller senders are judged more favourably with DMARC as well.

Alignment is the tricky part. DMARC passes only if SPF or DKIM passes for the same domain shown in the From address. A newsletter tool that sends with bounce.toolmail.example and signs with toolmail.example can pass SPF and DKIM but still fail DMARC for example.com. The fix is to set up a custom sending domain in that tool. More in DMARC policy setup.

Reputation problems

If authentication passes and mail still lands in spam, mailbox providers probably don't trust the sender yet.

4. Your domain is new or has no history

A domain registered last week that suddenly sends hundreds of emails looks just like a spammer's throwaway domain. Mailbox providers build trust over time.

Start with normal person-to-person mail, the kind people reply to.
Increase volume gradually if you plan to send newsletters.
Keep marketing mail separate from day-to-day mail, using a subdomain such as news.example.com.

5. Your IP or domain is on a blocklist

If you send from shared hosting or a cheap VPS, the IP may already be listed because of someone else's behaviour. Check public blocklist lookup tools for your sending IP and domain. A reputable email provider monitors and manages its own sending IPs. Self-hosted servers also need a matching reverse DNS (PTR) record, or many receivers will distrust them.

6. Recipients complain or never engage

Every "Report spam" click hurts your reputation. Mail that is never opened, or deleted unread, sends a weaker signal in the same direction. Typical causes:

Sending to purchased or scraped lists.
Mailing people who signed up years ago and have forgotten you.
No easy way to unsubscribe, so people press "spam" instead.

Send only to people who asked for your mail, remove addresses that bounce, and make unsubscribing obvious.

Content and sending setup

7. Content that looks like spam

Content matters less than authentication and reputation, but it still counts:

A single large image with little text.
URL shorteners, or links whose visible text shows a different address from the real target.
Links to domains with a poor reputation.
Attachments such as .zip, .exe or macro-enabled Office files sent to strangers.
ALL-CAPS subjects, lots of exclamation marks, and "act now" urgency.
Broken HTML copied from a word processor.

8. Forwarding and mailing lists break authentication

When a message is forwarded or passes through a mailing list, SPF often fails because the forwarding server isn't in your record. DKIM usually survives unless the list changes the subject or body. That is one reason a valid DKIM signature matters so much.

9. You're sending from the wrong place

Website contact forms that send "from" your domain through the web server's local mail function are a classic cause of spam placement, because that server isn't in your SPF and doesn't sign with DKIM. Send them through authenticated SMTP on your real mail service instead.

10. Your MX and DNS basics are inconsistent

Receivers check that a domain looks like a real, working mail domain. A missing or broken MX record, mismatched hostnames or expired DNS settings are red flags. Read MX records explained to check the basics.

Quick reference table

Symptom	Likely cause	First fix
`spf=fail` or `permerror`	Sender missing, or over 10 lookups	One merged SPF record
`dkim=none`	DKIM not published or not signing	Publish your provider's DKIM records
`dmarc=fail` with SPF/DKIM pass	Alignment: a third-party domain is used	Custom sending domain in that tool
Everything passes, still spam	Reputation or content	Clean lists, slow ramp-up, simpler content
Only form emails land in spam	Sent through the web server	Send via authenticated SMTP

How Zomail helps keep your mail out of spam

When you add a domain to Zomail, a guided DNS page checks each record for you: verification TXT, MX mx.zomail.io, SPF with include:_spf.zomail.io, DKIM through two CNAMEs (zm1 and zm2) with automatic key rotation, DMARC, and MTA-STS/TLS-RPT. You can download a zone file, or use one-click Domain Connect with DNS providers that support it. A DMARC reports dashboard shows who is sending as your domain and their pass rates, which is the quickest way to find a forgotten tool that fails alignment. Outbound spam scoring also helps protect the shared reputation of everyone's mail. The getting started guide walks through setup.

If you want authentication set up correctly from day one rather than fixed after the fact, Zomail Cloud is priced per mailbox per month. See the pricing page for current prices.

FAQ

Why are my emails going to spam in Gmail but not Outlook?

Each provider weighs signals differently. Gmail relies heavily on domain reputation and on how its users engage with your mail. Check the authentication results in the Gmail message source first. If everything passes, look at Google Postmaster Tools and at your list quality.

How long does it take to fix emails going to spam?

DNS fixes such as SPF, DKIM and DMARC take effect within minutes to hours. Reputation recovers more slowly, usually over days or weeks of consistent, wanted mail.

Does asking recipients to mark "Not spam" help?

Yes. A recipient moving your message to the inbox or adding you to contacts is a positive signal for that mailbox, and often for your reputation in general. It doesn't replace fixing authentication, though.

Can a new domain send email without going to spam?

Yes, if authentication is complete from the start and volume grows gradually. Begin with ordinary one-to-one mail before sending any bulk campaigns.