How do I fix Apple Mail DMARC failure when sending from Gmail with a non-Gmail domain?

Key findings

• Authentication mismatch: The core issue is a DMARC failure, not necessarily a DKIM failure, driven by a mismatch between the smtp.mailfrom (Gmail address) and header.from (your custom domain).
• Gmail's override behavior: When using a personal Gmail account's SMTP server, Gmail replaces the mail from header with the authenticating Gmail user's credentials, causing DMARC alignment to break for the custom From header domain. This often leads to a DMARC verification failed error.
• Apple mail client misconfiguration: The problem typically stems from Apple Mail being configured to send through a personal Gmail account's SMTP server instead of the correct Google Workspace SMTP server for the custom domain.
• Lack of DKIM signature for custom domain: The headers may show a Google DKIM signature, but not one for your custom domain, indicating the custom domain's Google Workspace account is not properly signing outgoing mail.

Key considerations

• Correct SMTP server configuration: The primary fix involves changing the outbound SMTP server in Apple Mail to use the Google Workspace SMTP server associated with your custom domain. Ensure the credentials match your workspace account, not a personal Gmail account.
• Verify DKIM for custom domain: Confirm that DKIM authentication is properly set up and active for your custom domain within your Google Workspace admin portal. If your DKIM is from domain mismatch then this problem is common.
• Review email headers: Examine the Authentication-Results section of your email headers for detailed insights. Tools like Kinsta's DMARC guide provide steps for fixing DMARC errors. See our guide on how to troubleshoot DMARC failures.
• Separate personal and business accounts: Avoid using a personal Gmail account for sending emails from a business domain to prevent authentication conflicts and ensure proper DMARC alignment.

Key opinions

• Client misconfiguration is common: Many marketers find that their email client (like Apple Mail) is simply set up incorrectly, defaulting to an unintended SMTP server.
• Expect DMARC failure with domain mismatch: It's widely understood that attempting to send from a custom domain via a personal Gmail account's SMTP server will inevitably lead to DMARC failure due to sender identity conflicts. For more context, see why DMARC fails when SPF and DKIM pass.
• Simplicity of solution: The fix is often straightforward: a simple toggle or selection in the mail client's settings to choose the correct outbound SMTP server.
• Importance of proper authentication: Marketers recognize that correct authentication (SPF, DKIM, DMARC) is crucial for email deliverability, especially with new Google and Yahoo requirements.

Key considerations

• Double-check SMTP settings: Always verify that Apple Mail (or any client) is configured to use the SMTP server of the domain you are sending From.
• Understand Return-Path behavior: Learn how Return-Path changes based on the sending server and how this affects SPF and DMARC alignment.
• Test thoroughly: After making configuration changes, send test emails to various providers (Gmail, Outlook) and check headers to confirm authentication passes. You can use our free email testing tool.
• Check Google Workspace DKIM setup: Ensure that DKIM is properly enabled and configured for your custom domain within Google Workspace, as this is essential for passing DMARC with DKIM alignment.

Key opinions

• SMTP mailfrom override: When connecting to Gmail's SMTP from a mail client, Gmail replaces the mail from with the authenticating Gmail user's credentials, causing DMARC to fail for custom domains.
• Client vs. server distinction: Apple Mail is a client, not a server; it requires an outbound SMTP server configured to sign emails with the correct domain's DKIM.
• DMARC failure is due to alignment: The issue is that the header.from domain (your custom domain) is not aligning with the authenticated smtp.mailfrom domain (Gmail). Find out more in our guide, a simple guide to DMARC, SPF, and DKIM.
• Common user error: Users often confuse accounts and servers, especially when naming them generally (e.g., 'Gmail'), leading to incorrect SMTP server selection.

Key considerations

• Configure Apple Mail correctly: Ensure the Apple Mail client uses the Google Workspace credentials and the corresponding SMTP server for the custom domain, not a personal Gmail account.
• Check Authentication-Results: Always inspect full email headers, particularly the Authentication-Results section, as it provides definitive information on SPF, DKIM, and DMARC passes or failures. This is a crucial step for troubleshooting DMARC reports from Google and Yahoo.
• Avoid implicit forwarding: Be aware of scenarios where mail clients or services implicitly forward emails, which can break DMARC alignment unless properly configured. Learn how to troubleshoot and fix SPF and DMARC settings.
• Check for DKIM signing issues: Confirm that the outbound server is indeed signing with your cooalliance.com DKIM key, not just a Google key. According to SendLayer, proper authentication is key.

Key findings

• Authentication is mandatory: Setting up SPF and DKIM before DMARC is crucial to avoid email delivery issues, as authentication is now a baseline requirement from major mailbox providers.
• DMARC reports provide insight: DMARC provides regular reporting on authentication failures and unauthorized sending attempts, which is invaluable for diagnosing issues.
• DMARC policy impact: A DMARC policy set to 'quarantine' or 'reject' is necessary for certain features, such as Apple Branded Mail, and helps enforce sending domain authentication.
• Common causes of failure: DMARC failures can occur if an email domain has been blocklisted due to abuse (e.g., spam) or if sender identification (SPF/DKIM) does not align with the From header.

Key considerations

• Prioritize DMARC implementation: Implement DMARC email authentication for all sending domains to meet evolving industry standards and ensure message deliverability.
• Ensure domain impersonation is avoided: Actively work to ensure that there is no domain impersonation in the FROM headers, as this is a direct cause of DMARC failures and can lead to being placed on a blocklist or blacklist. Check what happens when your domain is on an email blacklist.
• Monitor DMARC compliance: Regularly check DMARC compliance reports to identify issues with email authentication. This helps to promptly address any reasons for DMARC failures, such as a blocklisted domain.
• Verify DMARC policy for services: If using specific services like Apple Business Mail, ensure your DMARC policy is robust (e.g., p=quarantine or p=reject) as required for full functionality. Consult Email on Acid's guide to DMARC policies for more details. For common issues with Google Workspace, refer to fixing common DMARC issues.