Why does SPF fail for Google Apps with passing DKIM when using Google Calendar invites?

Marketer from Email Geeks confirms that Google Calendar Notifications rewrite the Return-Path address to "calendar-server.bounces.google.com" which fails Alignment, thus fails DMARC, but custom DKIM is implemented to handle these scenarios.

Email marketer from SparkPost Blog explains that third-party services like Google Calendar often send emails on your behalf, and their SPF records may not align with your domain. This causes SPF failures. However, if you've implemented DKIM correctly, the email will still pass DMARC authentication. Ensure DKIM signatures are valid and aligned.

Email marketer from MXToolbox shares that even if an SPF check fails, if the DKIM check passes and the d= domain in the DKIM signature matches the domain in the From: header, DMARC can still pass. Google Calendar's SPF failures are often mitigated by a properly configured DKIM.

Email marketer from Stack Overflow explains that when Google Calendar sends out invites on your behalf, the Return-Path is rewritten to a google.com domain. Because of this rewrite, SPF checks will fail if the recipient's mail server checks SPF records, however DKIM can pass because the message content is signed by your domain.

Email marketer from Email Delivery Forum mentions that a common cause of SPF failures is the usage of calendar invites. When Google sends an invite, they are acting as a third party and are rewriting the Return-Path to Google's infrastructure. If you have a valid DKIM configuration the email will pass DMARC.

Email marketer from Reddit explains that the problem with Google Calendar invites is due to Google's handling of the Return-Path. When sending invites, Google changes the Return-Path to their domain, causing an SPF failure. Since you've properly set up DKIM, the DMARC policy will be satisfied, even if SPF fails.

Email marketer from SendGrid states that even if SPF fails because Google is sending the email on your behalf with their Return-Path domain, DMARC can still pass if DKIM is set up. DKIM passing indicates that the email content hasn't been tampered with and that it is genuinely from your domain.

Email marketer from EmailGeek Forums shares that Calendar invites sent from Google Calendar will often fail SPF because the Return-Path domain is rewritten to a Google domain. The EmailGeek states that this is a common issue and the DKIM signature is what ultimately confirms that the email is legitimate, thereby satisfying DMARC.

Expert from Email Geeks suggests that weird forwarding set up for a mailbox that gets lots of mail, using Gmail’s forwarding could cause SPF alignment failures, or not having DKIM fully set up in Google Apps for this domain could result in some sends having a different return-path header with a default domain, which would also count as an SPF failure.

Expert from Word to the Wise shares that it is important to have both SPF and DKIM implemented in order to avoid issues with Google Calendar. Even though SPF can fail with calendar invites due to google re-writing the return-path domain, DKIM alignment will ensure that the DMARC will be legitimate.

Expert from Email Geeks clarifies that as long as DKIM is passing, DMARC is passing, so there is no issue to raise with Google.

Expert from Spam Resource explains that the main reason for SPF failures with Google Calendar invites is that Google rewrites the Return-Path to their own domain for handling bounces. Even though SPF may fail, the email can still pass DMARC if DKIM is properly set up, as DKIM validates the email's content and origin.

Expert from Email Geeks explains that the Google Calendar invites rewrite the Return-Path address to "calendar-server.bounces.google.com" which fails SPF alignment, thus failing DMARC, but custom DKIM is there to save the day.

Email marketer from Cloudflare explains that DKIM creates a digital signature that validates messages. If SPF alignment fails the messages can still pass DMARC authentication by using a DKIM signature. Google Calendar uses their own infrastructure which can cause SPF to fail.

Documentation from DMARC.org explains that SPF and DKIM are different authentication methods. SPF checks if the sending IP address is authorized to send email for the domain in the MAIL FROM address. DKIM uses cryptographic signatures to verify the message's integrity and that it came from the claimed sender. Even if SPF fails, a passing DKIM signature can still allow the email to pass DMARC checks if the 'd=domain' aligns with the 'From:' domain.

Documentation from Microsoft explains that SPF and DKIM should be used together. SPF helps prevent spoofing, while DKIM provides message integrity. In scenarios where SPF fails due to legitimate forwarding, DKIM still ensures the message is trustworthy. Implement both SPF and DKIM for the strongest authentication.

Documentation from Google Workspace Admin Help states that DKIM can authenticate the content of the message, verifying it wasn't altered during transit. SPF authenticates the sender's IP address. Even if SPF fails due to forwarding or other issues, DKIM can still pass, ensuring the message is legitimate. Calendar invites use Google's infrastructure which may not align with your SPF record, but DKIM ensures validity.

Documentation from RFC 7489 (DMARC Standard) defines that DMARC leverages SPF and DKIM to authenticate email. If SPF fails, DMARC relies on DKIM. If DKIM passes with proper alignment, the DMARC check passes even if the SPF check fails. Google Calendar invites leverage this functionality with properly setup DKIM