Fix email delivery issues for error code 5.7.133 in Exchange Online

It's frustrating when you get an error after sending an email message. This topic describes what you can do if you see error code 550 5.7.133 in a non-delivery report also known as an NDR, bounce message, delivery status notification, or DSN). You'll see this automated notification when the recipient is a group that's configured to reject messages from external senders (senders from outside the organization).

Email user icon I got this bounce message. How do fix it? Email admin icon I'm the group owner or email admin. How do I fix this?

I got this bounce message. How do I fix it?

Only the group owner or an email admin in the recipient's organization can fix this issue. Contact the group owner or email admin and refer them to this information so they can try to resolve the issue for you.

I'm the group owner or email admin. How do I fix this?

The two methods that will allow an external sender to send messages to the distribution group in your organization are described in the following sections.

To open the Exchange admin center (EAC), see Exchange admin center in Exchange Online.

Method 1: Allow all internal and external senders to send messages to this group

    1. In the EAC, go to Recipients > Groups > select the group from the list, and then click Edit Edit icon.

    Finding groups in the Exchange admin center

  1. In the group properties dialog box that opens, go to Delivery management > select Senders inside and outside of my organization.

    Use the Exchange admin center to solve DSN 5.7.133 and allow senders

  2. Click Save.

Method 2: Use the group's allowed senders list

Instead of allowing all external senders to send messages to this group, you can use the group's allowed senders list to selectively allow messages from all internal senders and the specified external senders.

Notes:

  • To add an external sender to a group's allowed senders list, you must first create a mail contact or a mail user to represent the external sender in your organization.

  • To add everyone in your organization to a group's allowed sender's list, you can create a distribution group or a dynamic distribution group that contains everyone in your organization. After you create this group, you can add it to the group's allowed senders list.

  • The group's allowed senders list is completely different from the organization's allowed senders list for anti-spam that you manage in the EAC at Protection > Spam filter.

To configure the group's allowed senders list, open the EAC do the following steps:

  1. Go to Recipients > Groups > select the group from the list, and then click Edit Edit icon.

  2. In the group properties dialog box that opens, go to Delivery management and configure the following settings:

    • Select Senders inside and outside of my organization.

    • Click Add Add icon. In the Select Allowed Senders dialog box that opens, select and add the external senders and the all internal users group. When you're finished, click OK.

      Add allowed external sender to a distribution group to help solve NDR 5.7.133

  3. Click Save.

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See also

Email non-delivery reports in Exchange Online

Create and manage distribution groups in Exchange Online.