Public folders stop receiving mails with reason: 550 5.4.1 []: Recipient address rejected: Access denied

Question

Hello,

our Office365 account is working fine since years.

We have public folders to receive mails to addresses like '******@ourdomain.com".

Some time ago there were issues, we needed to adjust rights and then it worked fine again.

Until now - since some day in June the public folders do not accept mails from the outside any longer (e.g. from Gmail or GMX).

The sender gets a "Mail delivery failed: returning message to sender" error, with that message:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of

its recipients. This is a permanent error. The following address(es)

failed:

******@ourdomain.de:

SMTP error from remote server for RCPT TO command, host: xxxxxxxmail.protection.outlook.com (213.199.154.999) reason: 550 5.4.1 [******@ourdomain.de]: Recipient address rejected: Access denied

No clue. Could someone help, please?

Thanks.

Marc

Answer 1

Hi Marc,

I find the issue is resolved. Here is the closure summary.

Issue Description:

================

When external mailboxes send emails to an Exchange Online public folder, an NDR bounced with the error: 550 5.4.1 Recipient address rejected: Access denied.

Root Cause/Analysis:

================

When the domain type is set to Authoritative, Directory Based Edge Blocking (DBEB) allows any SMTP address that has been added to the service, except for mail-enabled public folders.

Resolution:

================

Keep the domain type as Internal Relay.

Thanks,

Young

Answer 2

Hi Marc,

Thanks for the information in Private Message.  To my knowledge, the 5.4.1 external mail flow could occur when Exchange Online Protection rejects the coming messages because the Directory Based Edge Blocking (DBEB) doesn't recognize the public folder as a valid recipient in Exchange Online. A workaround for this issue is to covert the smtp domain from Anthoritative to Internal Relay. Please try it in your Exchange admin center and let us know if it works.

Best Regards,

Alex

Answer 3

Hi Marc,

Thanks for your efforts so far.

By checking the NDR you provided, we can see the email is sent to the public folder on a custom domain. By default, mail-enabled public folders are on the Office 365 default domain xxxx.onmicrosoft.com. Can you please let us know how you modified the email address to a custom domain? Did you use the PowerShell command Set-MailPublicFolder to do it?

Moreover, please use PowerShell to manage the permission by referring to Add-PublicFolderClientPermission. If the CreateItems permission does not work, please try a higher permission such as EditAllItems. (When doing all this, please keep the domain type as Internal Relay.)

And if the issue still exists, please run a message trace to look for the affected email, and see what it says from the trace result. You can reply to our private message again to provide the trace result.

Regards,

Allen

Answer 4

Hello Alex,

Thank you for your reply. It doesnt help.

I changed for that domain to 'Internal Relay', test unsuccessful, changed it back to 'Authoritative', test unsuccessful.

What next?

Thanks

Marc

Answer 5

Hi Marc,

 To better understand the problem, please provide us with the following information.

•    Do you mean that every external sender received NDR 5.4.1 when they send email to public folder address in your domain?

•    Does this issue happen to every public folder or specific public folder address?

•    May I know whether you have configured the domain type are Authoritative or Internal relay. You can check the status of the domain in the Exchange admin center by performing these steps:

1.    In the EAC, navigate to Mail flow > Accepted domains.

2.    Select the domain and click Edit icon

•    Which kind for environment do you set up? Is it Hybrid deployment?

•    Could you please provide us with the detailed Non Delivery Report (NDR without editing) and tenant domain (@contoso.com) via the private message for further analysis?

Moreover, please make sure the Anonymous users have got the enough permission so that they will be able to send emails to the public folder.

I have sent you private message and here is the link to access it: https://answers.microsoft.com/en-us/privatemessages/list

Best regards,

Shyamal