Why Your Emails Go to Spam

The short answer: Emails go to spam because the receiving provider doubts the sender. The usual causes, in order of frequency, are failing SPF, DKIM or DMARC authentication, a damaged sender reputation (complaints, bounces, bad lists), a blacklist listing, or content and formatting that looks like bulk mail. Open one spam-foldered message's headers first: they usually name the cause.

Start With the Evidence, Not a Guess

Most advice on this topic is a list of "spam words". That is rarely the real problem. Before changing anything, collect three facts:

1. Who is affected? Everyone at Gmail, only Outlook.com recipients, or only one company? A single recipient domain points to that provider's filtering or a blacklist they use. Everyone points to your domain.
2. Which mail? Only bulk sends from a marketing platform, or also one-to-one mail from your own mailbox? Bulk-only problems point to the platform's authentication setup or your list.
3. When did it start? A sudden change usually follows a DNS edit, a new sending tool, a migration, or a compromised account.

Then read the headers of a message that landed in spam. In Gmail: open the message, three-dot menu, Show original. Look at the authentication summary at the top, or search the raw text for Authentication-Results:

Authentication-Results: mx.google.com;
       dkim=fail header.i=@yourdomain.com header.s=selector1;
       spf=softfail (google.com: domain of transitioning bounce@yourdomain.com does not designate 198.51.100.24 as permitted sender) smtp.mailfrom=bounce@yourdomain.com;
       dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=yourdomain.com

Here all three checks failed, which is a configuration problem and not a content problem. The email header analyzer parses this block for you, and how to read email headers explains every field.

The Five Causes, Ranked by How Often They Are the Real Problem

1. Authentication Is Missing, Broken or Misaligned

SPF, DKIM and DMARC let a receiver verify that mail claiming to be from your domain really is. Failure modes worth knowing:

• A sender is missing from SPF. You added a newsletter tool, CRM or invoicing system and never added its include:. See adding third-party senders to SPF.
• SPF exceeds 10 DNS lookups. The result is permerror and SPF is treated as failed. See SPF too many DNS lookups.
• DKIM is not enabled. On Microsoft 365 you must turn on DKIM signing per domain yourself. A platform may also sign with its own domain, which passes DKIM but does not align with your From domain.
• Alignment fails. DMARC passes only if SPF or DKIM passes and the authenticated domain matches the visible From domain. A tool can show "SPF pass" and still produce dmarc=fail.
• DKIM breaks in transit. Mailing lists, forwarders and some security gateways rewrite the body. See DKIM signature failed.

Since February 2024, Gmail and Yahoo have required authentication for bulk senders, and enforcement has tightened since. The specifics are in Google and Yahoo bulk sender requirements. Check all three records with the SPF checker, DKIM checker and DMARC checker, or get one combined grade from the email security score.

2. Your Sender Reputation Has Dropped

Providers keep a running opinion of your domain and sending IP based on how recipients treat your mail. The signals that matter most:

• Spam complaints. Google's published guidance for bulk senders is to keep the user-reported spam rate below 0.10% and never reach 0.30%.
• Hard bounces. Repeatedly mailing addresses that do not exist looks like list scraping.
• Spam traps. Addresses that never opted in and only exist to catch careless senders. Old or purchased lists contain them.
• Engagement. Messages deleted unread, or never opened, count against you.
• Volume spikes. A quiet domain that suddenly sends thousands of messages looks like a hijacked account. A new domain needs a warm-up schedule.

Reputation is slow to build and fast to lose, so this is the cause to suspect when authentication passes and the problem is intermittent.

3. You Are on a Blacklist

If a DNS blocklist lists your IP or domain, receivers that query it will reject or junk your mail. This usually shows up as bounces rather than quiet spam-foldering, for example:

550 5.7.1 Service unavailable, Client host [198.51.100.24] blocked using Spamhaus

Run the blacklist checker. For how listings work, how to read results and how to get removed, see how to check an email blacklist.

4. The Message Itself Looks Like Bulk Mail

Content matters less than people think, but it tips borderline cases. Real contributors:

• A single large image with almost no text
• Link shorteners, or visible link text that shows one domain while the href points to another
• Links to domains with a poor reputation
• Missing plain-text alternative
• Broken or bloated HTML
• A misleading subject line or a "Re:" that is not a reply
• An attachment type such as .exe, .zip or macro-enabled Office files

Heavy use of words like "free" or "urgent" is a weak signal by itself. Over-optimising for it wastes time while the real cause (usually authentication) goes unfixed.

5. Sending Setup Mistakes

• The From address uses a free mailbox domain such as gmail.com while the mail is sent through your servers. Gmail's DMARC policy will fail it.
• Mail is sent from an IP with no reverse DNS (PTR) record, or a PTR that does not match the forward hostname.
• Sending from a shared IP whose other tenants are abusing it. Common on cheap shared hosting.
• A missing one-click unsubscribe on promotional mail, which Gmail and Yahoo expect from bulk senders.

Error Message to Cause to Fix

When mail is rejected rather than junked, the bounce text tells you the cause. Real-world Gmail wording:

Exact wording and enhanced status codes vary by provider and can change, so use these as a guide, not an exhaustive list.

Diagnose in This Order

1. Check authentication with the email security score. If SPF, DKIM or DMARC fail, stop here and fix them. Everything else is secondary.
2. Confirm alignment in a real message's headers, not only in DNS. A valid record can still fail for a specific sender.
3. Check blacklists with the blacklist checker.
4. Check your reputation dashboards. If you send meaningful volume to Gmail, use Google Postmaster Tools. For Microsoft, Smart Network Data Services (SNDS) shows traffic for IPs you control.
5. Review the list and content: bounce rate, complaint rate, age of the list, link domains, plain-text part.
6. Send test messages to seed accounts at several providers and compare placement. How to test email deliverability covers the method.

Fix Order

Fix authentication first. Publish a correct SPF record, enable DKIM for every sending service, and add a DMARC record starting at p=none with a rua address. The SPF generator, DKIM generator and DMARC generator build the records. Platform walkthroughs: Google Workspace DMARC and Microsoft 365 authentication.

Then remove the cause of any listing, such as a compromised mailbox or a bad list, before requesting delisting. Otherwise you are likely to be listed again.

Then clean the list. Remove hard bounces, suppress contacts who have not engaged in many months, and never mail purchased lists.

Then restore reputation slowly. After a reputation hit, reduce volume to your most engaged recipients and rebuild. Recovery takes time, and no tool shortens it reliably.

Finally, polish content. Add a plain-text part, use real link domains, balance text and images, and include a working unsubscribe.

Quick Reference

Frequently Asked Questions

Why do my emails go to spam even though SPF, DKIM and DMARC pass?

Authentication proves identity, not trustworthiness. If it passes, look at reputation (complaints, bounces, engagement), the links and content in the message, and whether the IP or domain is blacklisted. A new domain with no sending history is also treated cautiously.

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

Gmail weighs recipient behaviour heavily. If many Gmail users ignore or report your mail, your Gmail placement drops while other providers are unaffected. Check Google Postmaster Tools for spam rate and compliance status, and confirm you meet Google's sender requirements.

Can I fix emails going to spam by avoiding spam words?

Rarely. Modern filters weigh authentication, reputation and recipient engagement far more than individual words. Cleaning up wording helps only after the technical causes are ruled out.

How long does it take to get out of the spam folder?

If the cause was a failed DNS record, placement can recover within hours to days once the record is fixed and caches expire. Reputation damage from complaints or bad lists takes longer, and depends on how consistently you send good mail afterwards.

Should I ask recipients to mark my email as "not spam"?

For a small, known audience it helps, because positive actions improve how that provider treats you. It is not a substitute for fixing authentication, and it does not scale to a large list.

Next Step

Run the free email audit to see your SPF, DKIM, DMARC and blacklist status together. If you would rather have it fixed and verified for you, see our email security setup service.