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Email can land in Spam even when SPF, DKIM, and DMARC are configured correctly. The receiving provider makes the placement decision using a mix of authentication, sender reputation, complaints, list quality, message content, sending patterns, and recipient or organization policies. Start with the affected message and the scope of the problem; then use its headers and provider-specific diagnostics to find the cause before changing settings.
First, identify what “goes to spam” means
Spam placement is different from a rejected message, a bounce, or a recipient-side rule. Establish which outcome occurred and how broadly it affects delivery before changing DNS or rewriting the message.
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- Save a copy of a message that landed in Spam or Junk, including its full headers.
- Check whether the problem affects one recipient, one mailbox provider, or recipients across several providers.
- Separate messages delivered to Spam or Junk from messages rejected or bounced, and from messages moved by a recipient’s own rule.
This distinction narrows the investigation: a provider-specific problem points toward that provider’s filtering or policy, while a failure across providers may indicate a sender-wide issue.
Read authentication results on the affected message
Inspect the message’s Authentication-Results header for SPF, DKIM, and DMARC results. These results show how the receiving system evaluated that particular message; a separate DNS lookup or configuration check does not prove that the message passed authentication. Google Workspace’s DMARC troubleshooting guidance recommends checking headers and reports when diagnosing failures.
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For Gmail, Google’s email sender guidelines say senders need SPF or DKIM authentication. Senders delivering more than 5,000 messages per day to Gmail are subject to additional bulk-sender requirements, including SPF, DKIM, and DMARC. For direct mail in this category, the visible From domain must align with the authenticated identity.
DMARC passes when at least one of SPF or DKIM both authenticates and aligns with the domain shown in the visible From address. A message can therefore fail DMARC even if SPF or DKIM passes on its own, if the passing identity does not align. Make sure SPF includes every authorized third-party sender, and configure custom-domain DKIM or an aligned MAIL FROM identity where needed. Microsoft explains alignment and third-party sender scenarios in its DMARC setup guidance.
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Authentication is important, but it is not an inbox guarantee. Google says authenticated messages are less likely to be rejected or marked as spam; reputation, complaints, content, and recipient policies can still affect placement.
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Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →If authentication passes, check sender health
Review domain and IP reputation, spam complaints, list accuracy, recent volume changes, and any recent move to new sending infrastructure. Microsoft lists sending IP, domain, authentication, list accuracy, complaint rates, and content among filtering factors. It specifically describes junk-mail complaint rate as a principal factor in sender reputation. A new sending IP may also have little established reputation.
For mail sent to personal Gmail accounts, Google Postmaster Tools provides dashboards for spam rate, IP and domain reputation, feedback-loop data, authentication, encryption, and delivery errors. These are provider-specific signals, not a universal score for all recipients.
For Gmail senders, Google’s 2024 sender requirements say the spam rate reported in Postmaster Tools must remain below 0.3%. The threshold is tied to Google’s reporting, not to a generic spam score from a third-party checker.
Review content, volume, and subscription practices
Content can contribute to filtering, but changing a subject line or removing a single phrase is not a universal fix. Microsoft’s anti-spam protection FAQ lists examples of content characteristics that may trigger filtering, including excessive links, URL shorteners, form tags, embedded scripts, and image-only content.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsFor Gmail marketing and subscribed messages, Google requires one-click unsubscribe and a visible unsubscribe link in the message body. Google also recommends consistent sending rather than bursts and gradual increases in volume. Review whether the sending schedule or subscription process changed around the time placement worsened.
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Check Microsoft 365 and organization-level filtering
If the affected recipients use Microsoft 365, filtering can also reflect tenant or mailbox settings rather than a sender-wide defect. Microsoft identifies bulk classification, mail-flow rules, anti-spam policy settings, and a user’s Blocked Senders list as possible causes.
- Inspect the affected message’s
X-Forefront-Antispam-ReportandAuthentication-Resultsheaders. - Use Microsoft 365 Message trace to follow the message through mail flow and identify its handling.
- If the message appears to be a false positive, submit it for analysis through the appropriate Microsoft workflow.
Microsoft’s anti-spam FAQ cautions that broad allowlists can let malicious mail bypass filtering. Allowlisting should not be the first response to unexplained spam placement.
Make one evidence-based correction, then monitor
Use the evidence from the affected message and relevant provider tools to choose the fix. Correct an authentication or alignment failure if one appears; remove invalid or unwilling recipients if list quality is the problem; address relevant content or sending-pattern issues; or have an administrator inspect recipient-side policy when filtering is local to an organization.
After the change, monitor the same provider-specific delivery, reputation, and error signals that identified the issue. A DNS correction cannot by itself repair a complaint, poor list quality, or a recipient policy. Google’s Postmaster Tools dashboard documentation describes the Gmail signals available for that follow-up.
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