Security Policy Errors

How to Fix Outlook Emails Going to Junk Due to ARC Failure

Rana Garcia Oct 13, 2026 868 views

Question details

Users need to resolve an issue where legitimate emails routed through Microsoft servers are incorrectly delivered to the Junk Email folder due to ARC and DKIM authentication failures.

How to Fix Outlook Emails Going to Junk Due to ARC Failure

Product: Microsoft Outlook
Device & OS: not provided
Scenario: Sending or receiving legitimate emails that end up being flagged as spam by Microsoft's email security filters.
Observed behavior: Legitimate messages are delivered to Junk Email, and examining the message headers reveals an 'ARC cv=fail' error along with DKIM-related authentication failures.

Before you start

Before troubleshooting, ensure you have access to the complete email message headers of the affected emails and, if you are the sender, administrative access to your domain's DNS management portal.

Solution 1Recommended

Review Sender Domain Authentication (SPF, DKIM, and DMARC)

Correcting your domain's DNS records prevents Microsoft's spam filters from flagging your emails as junk due to failed sender authentication.

DKIM and SPF records are used to verify that an email was actually sent by the domain owner. Microsoft aggressively increases the spam score when these checks fail. If your domain's authentication is misconfigured, ARC (Authenticated Received Chain) will ultimately fail when routing through Microsoft servers.

Check SPF records

Log into your DNS provider's dashboard and ensure your TXT SPF record includes all IP addresses, web hosts, and third-party services authorized to send emails on your behalf.

Validate DKIM signatures

Confirm that your DKIM keys are valid, enabled in your email host settings, and correctly published in your DNS. Missing or altered DKIM signatures will directly cause ARC checks to fail.

Audit DMARC policies

Review your DMARC record to ensure it aligns correctly with your SPF and DKIM setup. Consider setting the policy to 'p=none' temporarily while monitoring XML failure reports to pinpoint the source of the issue.

Review Sender Domain Authentication (SPF, DKIM, and DMARC)

DNS Propagation Delay: Keep in mind that any modifications made to your SPF, DKIM, or DMARC DNS records can take up to 48 hours to fully propagate across global mail servers.

Solution 2

Analyze Message Headers for Intermediary Modifications

ARC failures frequently occur when an intermediary server modifies the email content or headers during transit, breaking the digital signature.

Solution 3

Perform a Message Trace via Microsoft 365 Admin Center

If you are the recipient using Microsoft 365, an IT administrator can trace the exact spam verdict and implement bypass policies if the sender is trusted.

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Frequently Asked Questions

What does 'ARC cv=fail' mean in my Outlook email header?

An 'ARC cv=fail' result indicates that the Authenticated Received Chain chain validation failed. This usually occurs when the email fails initial SPF or DKIM authentication checks at the source, or if an intermediary routing server modifies the email's content or headers before it reaches the final Microsoft server.

Can an email recipient fix an ARC failure on their own?

Generally, no. ARC failures are heavily dependent on the sender's domain DNS configuration (SPF, DKIM, DMARC) or routing infrastructure. Recipients cannot fix the sender's authentication, but they can ask their Microsoft 365 IT administrator to whitelist the sender's domain to prevent future emails from going to Junk.

Why are only some emails from a sender going to the Junk folder?

This inconsistency often happens if the sender uses multiple mailing systems or third-party marketing services. If certain sending IP addresses or services are included in their SPF records while others are forgotten, the emails originating from unauthorized IPs will fail authentication, trigger an ARC failure, and route directly to Junk.

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