Fixing Google Calendar Invites That Fail DMARC Checks

The email authentication landscape changed permanently in 2024, says Brad Slavin, General Manager of DuoCircle. Google, Yahoo, and now Microsoft all require DMARC. What used to be a best practice is now a hard prerequisite for reaching inboxes. Organizations that delayed are now paying the price in deliverability.

DMARC (RFC 7489) ties SPF and DKIM together by requiring alignment between the envelope sender and the visible From header. According to Google’s February 2024 bulk sender requirements, a DMARC policy of at least p=none is now mandatory for any domain sending 5,000+ messages per day to Gmail users.

Google Calendar invites fail DMARC checks when the recipient replies to them, and the response goes back to **Google’s servers instead of the sender’s domain. This happens because the ‘From’ address and the originating server don’t match.

This failure also occurs due to the fact that Google uses shared IP addresses to send Google Calendar invites. So, if any of these IP addresses have had spam complaints registered against them, the invites sent using them won’t go through DMARC checks. You can fix the issue by adding Google’s DKIM record to your DNS and enabling DKIM authentication on Google Workspace.

How to Fix the Google Calendar Invite Issue in 2024?

As suggested above, you can fix this in simple steps.

Step 1: Add Google’s DKIM Record to Your Domain’s DNS Zone

• Visit the Google Workspace admin console.

• Select ‘Settings for Gmail.’

• Then, select ‘Authenticate Email.’

• Copy the record that will be used by Google to sign your emails for authenticity and integration.

• Add the copied DKIM to _google._domainkey.

Step 2: Enable DKIM Authentication on Google Workspace

• Visit the Google Workspace admin console.

• Select ‘Settings for Gmail.’

• Then, select ‘Authenticate Email.’

• Click on ‘Start Authentication.’

Additional Best Practices

To increase the chances of Google Calendar invites’ emails passing DMARC, you can also follow some best practices-

1. Use Custom Domain For Sending

Avoid using a generic domain like @gmail.com or @google.com. Instead, use a custom domain that aligns with your company’s name. This better aligns the ‘From’ address in the email headers and the sender’s domain.

2. Implement SPF and DKIM

Ensure that your domain has DKIM and SPF records properly configured. DKIM (DomainKeys Identified Mail) adds a digital signature to emails, while SPF (Sender Policy Framework) specifies which servers are **authorized to send emails on behalf of your domain. These authentication mechanisms help validate the legitimacy of emails sent from your domain, including Google Calendar invites. Explore our full DMARC toolset to generate and test each record.

3. Safelisting Google’s IP Addresses

If your DMARC policy is set to quarantine or reject emails that fail authentication checks, consider safelisting Google’s IP addresses to ensure that legitimate Google Calendar invites sent from Google’s servers are not inadvertently blocked or marked as spam.

4. Set up DMARC Policy

Configure a suitable DMARC policy for your domain to specify how receiving email servers should manage emails that fail DMARC checks. We suggest that you begin with a monitoring policy (p=none) to keep an eye on DMARC alignment without impacting email delivery.

Once you’ve analyzed the results and ensured legitimate emails are passing DMARC checks, consider moving to an enforcement policy (p=quarantine or p=reject). Before you do, run a DMARC check to confirm your record is valid.

5. Monitor DMARC Reports

Choose to receive DMARC aggregate (RUA) reports and DMARC forensic (RUF) reports in your DMARC record and regularly monitor them with a DMARC monitoring service to **spot issues and anomalies related to Google Calendar invite emails . These reports help you with valuable insights into email authentication failures, enabling you to adjust your DMARC policy and authentication mechanisms as and when required.

For any help regarding DMARC reporting and monitoring, contact us.