An internal distribution list is being treated as an external organization email.

Question

Hi community,

Pretty simple question, I can't be bothered to wait for Microsoft Support and thought it would be more beneficial if more people could search and find an answer to this plain and boring question:

Why is an internal distribution list treated as an external when sharing files with the group?

Yes, I am aware that you normally cannot share attachments from sharepoint/onedrive with DLs but the crux of the matter is when an end user attempts it, they receive a message like the one below:

or

What is the logical explanation to this? Why is the distribution list containing only internal users of the organisation being treated as an external?

Answer 1

Hello, @Moshiur (Moshiur Khan),

Welcome to the Microsoft Q&A platform!

The issue you encountered often arises due to how distribution lists are configured and recognized within your organization's sharing policies. Here are a few potential reasons:

1. DL Configuration: Distribution lists might be configured in a way that makes them appear as external entities. This can happen if the DL includes external email addresses or if it is set up to allow external senders.
2. Security Policies: Your organization's security policies might treat DLs differently from individual user accounts. This is often done to prevent accidental data leaks, as DLs can sometimes include external members or be forwarded to external addresses.
3. SharePoint/OneDrive Limitations: SharePoint and OneDrive have specific sharing restrictions. They often do not support sharing files directly with DLs because DLs are not considered secure or verifiable recipients. Instead, they prefer sharing with individual user accounts or security groups.
4. Email Routing: If the DL is routed through an external connector or service, it might be flagged as external. This can happen even if all members are internal, due to the way the email routing is configured.

To solve your issue, it is recommended for you to consider:

1. Using Security Groups: Instead of DLs, use security groups or Microsoft 365 groups, which are better supported for file sharing.
2. Checking DL Membership: Ensure that the DL does not include any external addresses.
3. Reviewing Sharing Policies: Work with your IT department to review and possibly adjust the sharing policies and configurations.

If these steps do not resolve the issue, consulting with your IT department or SharePoint/OneDrive administrator may provide more specific guidance based on your organization's settings.

---

If the answer is helpful please click on ACCEPT ANSWER as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang