Allow External Senders to Email This Group

AD Group Allow External Senders - Easy365Manager

In some cases, external senders receive an NDR when sending an email to your distribution group.

This is often accompanied by NDR error code 550 5.7.133 and an error message similar to the following:

Remote Server returned ‘550 5.7.133 RESOLVER.RST.SenderNotAuthenticatedForGroup;
authentication required; Delivery restriction check failed because the sender was
not authenticated when sending to this group’

The root cause of this issue is that distribution groups do not accept emails from external senders by default.

Fixing this error with Easy365Manager is very easy:

Open up Active Directory Users & Computers, select properties of the affected group, and click the “Office 365” tab.

Click the Delivery Restrictions button and uncheck the “Require that all senders are authenticated” checkbox:

Click OK to commit the change.

(for faster replication to Office 365, select the “Synchronize AD with Office 365” checkbox before committing the change)

You can download a fully functional 30-day trial of Easy365Manager here.

The Easy365Manager trial is a simple .dll extension to Active Directory Users & Computers and makes no changes to your schema or infrastructure.

Fix 550 5.7.133 Using On-Premises Exchange

Without Easy365Manager, you’ll be facing the more cumbersome task of logging in to the Exchange on-premises admin center, locating the group, and configuring the setting:

AD Group - Allow External Senders - Exchange On-premises

After that, a remote PowerShell to your Azure AD Connect server is required to replicate the new configuration immediately.

(with Easy365Manager, both these steps are performed directly from group properties in AD Users & Computers)

Fix 550 5.7.133 Using Exchange Online

If your group is a non-synchronized Office 365 group, the configuration change must happen in Office 365.

You can use the Exchange Admin Center to find the group and change the configuration to allow external (non-authenticated) senders:

Office 365 Group - allow external senders

Consolidated AD and Office 365 Management

Many admins manage a plethora of technologies like AD, Office 365, WAN/LAN/WiFi networks, client and application deployment, server management, custom applications, and more.

If you find yourself working with a large set of technologies, you probably want to simplify your daily life.

Easy365Manager consolidates your AD and Office 365 management which provides a lot of benefits:

  • You don’t need to speculate about attribute authority (Easy365Manager will write to AD/Office 365 as needed)
  • You don’t need to switch between multiple web consoles  and PowerShell (everything is managed out of AD Users & Computers)
  • You can remove your on-premises Exchange Server (giving you 100% protection from future zero-day exploits targeting Exchange on-premises)

Easy Delegation of Semi-Complex Tasks

Even admins who work full-time focusing on AD and Office 365 can find a lot of benefits in running Easy365Manager.

With Easy365Manager, you can easily delegate semi-complex tasks like calendar permission configuration to your first-level support.

With Easy365Manager, any junior admin can configure calendar permissions with practically no instructions needed:

Delegating tedious day-to-day operations to front-line support allows backend admins to concentrate on more complex tasks like security, virtualization, serverless infrastructure, etc. Efforts that will bring real value to their business.

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