When you send an email using Outlook (or another email client) and it bounces back with the “message not delivered” event, you’ll often get the “Recipient Address Rejected. Access Denied” problem. This error message is typically linked to status errors 541 and 551.

After doing a thorough investigation into this issue, we were able to pinpoint a few typical situations that could be the root of this specific problem. When you attempt to send an outbound email, the following items may result in the error “Recipient Address Rejected. Access Denied“:

Recipient Address Rejected Access Denied

  • Non-Existing Email Address – One of the most frequent causes of this error is when you’ve recently sent an outbound email to a non-existent email address. The only workable solution in this situation is to confirm that you are sending the email to a legitimate inbox and, if necessary, change the recipient.
  • If you notice that this error occurs whenever an email attempts to exit your email client, a DNS problem may be to blame. If sending emails through your email provider’s online interface is acceptable but you consistently see an error with Outlook or Thunderbird (and the likes). In this situation, deleting your DNS cache ought to help you resolve the problem.
  • An anti-spam filter rejects emails – Another possibility is that an anti-spam filter is classifying your email as spam (if you have previously mailed to the same inbox). Asking the recipient to add you to their whitelist is the only solution in this situation to ensure that your emails are sent.
  • External emails are being blocked by DBEB. The issue is most likely brought on by DBEB if you previously configured Exclaimer Cloud with Microsoft 365 and encounter this error when sending emails to public folders. By making sure that the public folders are hosted on-premises in this situation, you can resolve the problem.

Now that we’ve covered every scenario in which you could be experiencing the “Recipient Address Rejected. Access Denied” error, let’s get to work troubleshooting it utilising a number of techniques that other affected users have found to be effective.

Please Enter the Proper Address.

Check to make sure the recipient email is right first before moving on. Check to see if the email you previously sent to this recipient still qualifies for passage via the mail gateway.

Make sure the recipients that return the ‘Recipient Address Rejected. Access Denied’ errors are still employees of your company if you’re having this problem with a gated email network.

If you’re using Exchange and find that the reason you’re receiving this problem is that you’re sending emails to people who don’t exist, one option is to create a CatchAll mailbox or address.

Move on to the next option below if you’ve just realised that you’re mailing to the right recipients but you’re still getting bounces with the ‘Recipient Address Rejected. Access Denied’ issue.

Clear Temp TCP/IP Data and Flush DNS

If the error only appears when you are connected to this specific network, you should start to worry about a possible DNS problem. The ‘Recipient Address Rejected. Access Denied’ error frequently occurs as a result of a protocol or data transmission issue.

If only one machine on the network is impacted in this scenario, you should presume that a network adapter bug or a problematic DNS range is keeping emails from leaving your gateway.

You should do a complete TCP or IP reset on the troubled computer (or on any machine in this network that is having this problem) to resolve the problem.

To flush the DNS and TCP/IP temporary data completely, follow the procedures below:

  1. To bring up the Run dialogue box, press Windows key + R. To open an elevated Command Prompt, put “cmd” into the text box and then press Ctrl + Shift + Enter.
  2. Click Yes to grant admin access when the User Account Control prompt appears.
  3. To do a DNS and TCP/IP reset, type the following instructions into the elevated Command Prompt and hit Enter after each one:

/flushdns in ipconfig

NBSTAT – R

NBSTAT – RR

internet reset all

netsh int reset ip

reset winsock netsh

  1. After each command has been properly executed, shut down the elevated Command Prompt.
  2. Open your email programme and see if you can send the same email to the same recipient to see if it still bounces.

Request Whitelisting From the Recipient

An anti-spam filter that is currently being employed by the receiving domain is another pretty frequent cause of this problem. Your message is most likely being returned because it is being flagged as spam due to your prior behaviour or the recipient’s actions.

Our research has revealed that there are three main causes for the “Recipient Address Rejected” message. Access Denied error when the recipient has installed a shield:

  • The spam filter’s recipient has previously flagged a message like this as spam. In this instance, all emails from the same sender and all emails that resemble the spam-designated email will be handled in the same manner.
  • Due to a domain policy that blacklists or deems all emails coming from this specific address as spam, emails are returned as undeliverable.
  • The email is received by the email domain, but because of a policy, it is separated and does not reach the target mailbox.

If any of the aforementioned scenarios apply to you, there is just one solution: ask the receiver to add you to their whitelist so they will get your email correspondence.

However, since your usual email bounces back, you’ll need to use a different email since you can’t actually accomplish anything from it.

Publicize the Exchange Mail Folders (if Applicable)

After setting Exclaimer Cloud via Microsoft 365, if you encounter the “Recipient Address Rejected. Access Denied” issue when attempting to send an email, the cause is most likely connected to the Directory-Based Edge Blocking (DBEB).

Just so you know, DBEB is set to reject external emails with addresses that are not present in the Azure Active Directory by default and is enabled in Microsoft 365.

However, it doesn’t imply that you don’t own such addresses. Since they are presently kept in a public folder mailbox that is not synchronised with the Azure Active directory, they are most likely seen as external.

There are three solutions you might try if you find yourself in this situation to enable you to correct the error:

  1. Verify that every public server is hosted on-site.
  2. Ensure that Exchange Online is hosting your public servers.
  3. Turn off Edge Blocking Based on Directory (Not Recommended)

Ascertain That Public Folders are Hosted Locally.

The public folders containing your emails will be hosted on-premises as a result of this process. Making some changes to the Optional Features requires accessing the Microsoft Azure Active Directory Connect screen.

By performing this action, the DBEB feature will make sure that the Mail Enabled Public Folder addresses are no longer regarded as invalid.

By making sure that each public folder is hosted on-premises, you can resolve the “Recipient Address Rejected. Access Denied” error by following the steps listed below:

  1. Open the Microsoft Azure Active Directory Connect screen.
  2. Once inside, choose Optional Features from the vertical menu on the left.
  3. Next, navigate to the right-hand section and choose the Exchange Mail Public Folder checkbox.
  4. After clicking Next to save the modifications, try sending the email again to check if the issue has been resolved.

Make Sure Online Public Servers are Hosted.

Remember that Mail Enabled Public Folders do not currently support Directory-Based Edge Blocking (DBEB). You’ll have to use a few workarounds as a result of that.

The first workaround is to set up an exception rule in the Mail flow menu so that emails sent to Public folders are no longer forwarded to Exclaimer Cloud.

To guarantee that the public servers are hosted online, adhere to the directions below:

  1. Begin by using your account to log into Exchange Online.
  2. After logging in with your account, select Mail flow from the menu, then click the rules tab.
  3. Click on Edit after choosing Identify Messages to transmit to Exclaimer Cloud from the list of possible rules.
  4. Scroll all the way to the bottom of the section in the ediable menu and select Add Exception (under Except If).
  5. Choose Recipient…Is this person from the list of alternatives.
  6. Select each mailbox that contains a public folder when the Select Member’s dialogue appears.
  7. To enforce the modification, click Add at the very end, then click Ok and save.

Turn off Directory-Based Edge Blocking

Although we don’t advise it, you can also completely disable the Directory-Based Edge Blocking mechanism to stop the DBEB from preventing access to your emails.

Follow these directions to do this:

  1. Use your account to sign in to Exchange Online.
  2. After successfully signing in with your account, navigate to Mail flow and use the context menu that just appears to select the Accepted domains category.
  3. After that, choose the public folder’s root domain and click Edit.
  4. To effectively disable DBEB, select Internal relay under This allowed domain is and click Save.