Fix Error 554 5.7.9 DMARC Policy Rejection for Calendar Invitations
Question details
Users receive a 554 5.7.9 error due to DMARC policy when sending Google Calendar invitations to Yahoo or Sky email addresses.
- Product
- Microsoft 365 / Outlook / Google Calendar
- Device & OS
- not provided
- Scenario
- Sending Google Calendar invitations to external email addresses like Yahoo or Sky from Microsoft 365 or Outlook.
- Observed behavior
- Invitations are rejected and returned to the sender's spam folder with Error 554 5.7.9 because they fail the recipient's DMARC authentication.
Verify the exact error code in the bounced email message and check if your sender domain allows you to modify its DNS and DMARC records.
Review Sender Domain DMARC and DNS Settings
If you use a custom domain, updating your SPF, DKIM, and DMARC records can ensure your calendar invitations pass recipient authentication checks.
Email providers like Yahoo and Sky enforce strict DMARC policies. If the Google Calendar invitation appears to come from your domain but isn't properly signed by your DNS records, it will be rejected.
Log in to your domain registrar's DNS management console.
Verify that your SPF record includes Google and Microsoft servers if you send calendar invites from both platforms.
Ensure DKIM is enabled and actively signing messages in your Google Workspace or Microsoft 365 admin center.
Check your DMARC policy (TXT record _dmarc) and consider setting it to 'p=none' temporarily while troubleshooting alignment issues.
Test Invitations with Alternative Email Addresses
Determine if the DMARC rejection is isolated to specific strict providers like Yahoo or Sky by sending test invites to other domains.
Contact Provider Support for Authentication Issues
Since DMARC alignment between Google Calendar and Yahoo or Sky involves backend routing, contacting official support may be necessary.
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Frequently Asked Questions
What does Error 554 5.7.9 mean in email delivery?
Error 554 5.7.9 indicates that the receiving email server rejected the message because it failed DMARC (Domain-based Message Authentication, Reporting, and Conformance) policy checks, often meaning the sender's identity could not be verified.
Why are only Yahoo and Sky addresses rejecting my Google Calendar invites?
Yahoo and Sky have implemented very strict DMARC policies to prevent spoofing and spam. If an invitation forwarded or routed through Google Calendar breaks the original sender's authentication alignment, these providers automatically block it.
Can I fix the DMARC issue if I use a free Yahoo or Gmail account?
No, standard free email users do not have access to modify DNS or DMARC records for these domains. You will need to wait for Google and Yahoo to resolve their cross-platform alignment issues or use a workaround like sharing calendar links directly.
How do I find the email headers to see the DMARC failure?
Open the bounced return message in your Microsoft 365 or Outlook spam folder. Look for an option like 'View message details' or 'Properties' to see the raw internet headers, then search for the 'Authentication-Results' line to see the specific DMARC status.
