Fix email delivery issues for error code 5.7.13 or 5.7.135 in Office 365

This topic walks you through the steps for what to do if you see error code 550 5.7.13 or 550 5.7.135 in a nondelivery report (NDR). You'd see the NDR when an email is rejected because the recipient address is a public folder that is set up to reject messages sent from outside of its organization. Only an email admin for the recipient’s organization can change this.

I'm the email admin for the recipient. How do I allow the sender to send a message to this public folder?

There are two methods you can use to allow the sender to send a message to the public folder address shown in the NDR. Here's how.

Method 1: Allow anyone (both inside and outside your organization) to send messages to this public folder   

  1. In the Exchange admin center go to public folders > public folders .

    View public folders to help fix DSN 5.7.135
  2. From the displayed list of folders, select the public folder shown in the NDR, and then select Edit Edit icon .

  3. In the Public Folder dialog box, select mail flow settings .

  4. Under Message Delivery Restrictions > Accept message from, select All senders.

  5. Under Message Delivery Restrictions, clear the check box for Require that all senders are authenticated, and then click Save > Close.

    Public folder delivery restrictions to help fix DSN 5.7.135

Method 2: Create a custom allowed senders list for the public folder   

To accept messages from someone outside of your organization but still reject messages from everyone else outside of your organization, you can create a custom allowed senders list that includes both that person and everyone in your organization. This example shows how to set up an allowed senders list for a public folder.

  1. In the Exchange admin center, go to public folders > public folders.

    View public folders to help fix DSN 5.7.135
  2. From the displayed list of public folders, select the public folder referenced in the NDR, and then select Edit Edit icon .

  3. In the Public Folder dialog box, select mail flow settings.

  4. Under Message Delivery Restrictions, clear the check box for Require that all senders are authenticated.

  5. Select to Accept messages from > Only senders in the following list.

  6. Select Add Add icon .

  7. In the Select Members dialog box, select the members you want to add to the allowed senders list, then select Add, and then click Save > Close.

    Tips: 

    • To add someone from outside your organization to an allowed senders list, you must first create a Mail Contact for them. See Manage mail contacts to learn how.

    • To include everyone from your organization in the allowed senders list, create a distribution group (or a dynamic distribution group) that contains everyone in your organization. Then add that group to the allowed senders list. Learn how at Create and use distribution groups.

    custom allowed sender list for a public folder to help fix DSN 5.7.135

Notes: The allowed senders list referred to here is not the same as the Exchange Online Protection anti-spam allowed or blocked senders list, which you manage from Exchange admin center > Protection > Spam filter.

If you created an allowed senders list in either of these methods by choosing Only senders in the following list, the check box to require that all senders are authenticated doesn't apply. The allowed senders list overrides the other delivery restrictions.

Still need help with error code 550 5.7.13 or 550 5.7.135?

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See Also

What are Exchange NDR in Exchange Online and Office 365

Email in Office 365 for business – Admin Help

DSNs and NDRs in on-premises Exchange 2013 and Office 365

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