Email Delivery Dilemmas: Making Gmail and Microsoft 365 Play Nice


“How can one address the intermittent delivery failures occurring when emails are sent from a Gmail account to a Microsoft 365 Distribution List that includes external Gmail contacts as members? Despite ‘Allow external senders’ being enabled and proper SPF, DKIM, and DMARC configurations for the domain, emails from Gmail to the Distribution List do not consistently reach the Gmail contact members. This issue seems to have begun following Google’s security updates on February 1, 2024. It appears that Google may be intermittently blocking these emails, perceiving them as spoofing attempts since they originate from a Gmail address but are sent via a Microsoft server. I’m seeking a solution that doesn’t involve changing the sender’s address from Gmail and allows for reliable delivery within the Microsoft 365 tenant. Previous attempts to resolve this using shared mailboxes, email forwarding, inbox rules, and mail flow rules have been unsuccessful. Could Power Automate be a viable solution, or is there another method to ensure consistent email delivery to the Distribution List members?”


Email communication is the backbone of modern business operations, and ensuring its reliability is paramount. However, administrators often encounter challenges, such as intermittent delivery failures when sending emails from Gmail accounts to Microsoft 365 Distribution Lists with external Gmail contacts. This article aims to provide expert insights into addressing these issues.

The core of the problem lies in the security measures implemented by email services to prevent spoofing. Google’s recent security updates have heightened these measures, leading to the intermittent blocking of emails sent from Gmail accounts to Microsoft 365 servers, perceived as potential spoofing attempts.

Exploring Solutions

The solution must ensure that emails are delivered reliably without altering the sender’s Gmail address. Here are some strategies:


Review Email Authentication Records

: Double-check SPF, DKIM, and DMARC records to ensure they are correctly set up, as misconfigurations can lead to email delivery issues.


Configure Microsoft 365 Connectors

: Set up connectors in Microsoft 365 to establish a trusted relationship between the Gmail sender and the Microsoft 365 tenant.


Utilize Power Automate

: Create a Power Automate flow that triggers when an email is received by the Distribution List. The flow can then send a copy of the email from a Microsoft 365 address to the intended recipients, bypassing the direct Gmail to Distribution List path.


Implement Mail Flow Rules

: Although previous attempts were unsuccessful, revisiting mail flow rules with a focus on conditions and exceptions might yield better results.


Engage with Microsoft and Google Support

: Collaborate with support teams to identify any underlying issues that might be contributing to the delivery failures.


Intermittent email delivery failures can be frustrating, but with a systematic approach and the right tools, it is possible to find a solution. Power Automate offers a promising avenue, and with careful configuration, it could be the key to ensuring consistent email delivery to Microsoft 365 Distribution List members.

Please note that this article is a general guide and may not cover all specific technical details of your situation. For complex issues, consulting with IT professionals who specialize in email systems is recommended.

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