We are living in an era that heavily uses digital communication. From social media to official communications, from meetings to chats, digital communication is serving. However, it sometimes encounters limitations. Users face one such issue when using emails for communication: getting a recipient address rejected message.
If you have faced it recently or at any point, it is a bounce-back message with error codes. The most common ones are 551 and 541. Although, you might be scratching your head over what this message and codes mean?
Continue reading the upcoming sections; you can learn all about it in a few minutes.
Reasons for Recipient Address Rejected Error
The most common reason you can face a recipient address rejected message is when you try to use an email that is not valid. By valid, we mean that it either never was in existence or is no longer active.
In either case, the emailing system will not be able to send the message. The reason is that it could not identify the receiving address. But that is one of the several reasons causing this issue. Let’s understand them briefly.
Incorrect Email Address
The several email communication tools are smart enough to remember the email address you have used in the past. At the same time, there’s always room for more. But all its efforts will be lost if you make email address typos. As a result, you get failed delivery or related error messages.
A DNS or Domain Name System is the ability to translate domain names into unique IP addresses. This system uses a cache, which can get corrupted or outdated with time.
If this happens, you can face the recipient address rejected error with one or almost every email you are trying to send. This issue can occur with browser-based and various email apps. These include Google mail, Outlook, and more.
An anti-spam filter is a fantastic tool to rule out unnecessary emails. Yet again, it is only a tool that can sometimes mark genuine emails or even external emails as spam conversations. Also, this is specific to every user.
So, if your recipient has a spam rulebook for their inbox, you might receive the address rejection message.
DBEB Microsoft 365 Configurations
DBEB is Directory Based Edge Blocking available in the service network of Microsoft 365 organizations. It allows you as a user to reject emails to unidentified or invalid recipients.
However, this error arises after the Exclaimer Cloud configurations have been modified in most cases. This blocking service works for Exchange online mailboxes. It also works without Exchange online mailboxes available to different organizations and their respective users.
4 Ways To Fix Recipient Address Rejected Error
Now that you know the possible reasons behind this error, let’s move ahead and fix them to resolve the issue.
- Use the Correct Recipient Email Address
- Redo DNS Cache
- Request Addition To Whitelist
- Update Exchange Email Settings
1. Use the Correct Recipient Email Address
As simple as it sounds, you must ensure that the email address you are trying to connect with is valid. For this, you can take two possible checks:
1. Correct spelling
Let’s say you are about to send an email to a new user, and during verification, you find that you’ve got it spelled wrong. Or the system detected the issue and threw a recipient address rejected error.
But if you have not sent that email, you can always edit the client’s email address. As a result, the error message is gone.
2. Use Valid Email
Even though you have previously connected with a particular email user, the system still gives you email errors.
One possibility is that either the username or the email address you have is no longer valid. The recipients may have updated the address or moved out of that organization, so your email bounces.
2. Redo DNS Cache
As we have discussed, DNS uses cache. Doing so makes the process faster by storing previous behavior patterns for any task on your machine. But, if it fails to update itself with time, it can get outdated or even corrupt. And can be one of the reasons causing trouble with your requested action.
Therefore, let’s look at the steps to clear your DNS cache regularly. These steps will also incorporate updates on the TCP/IP data.
1. Open Command Prompt on your local machine as Admin. You can search for the apps or use the Windows+X key on the keyboard.
2. Use the following commands in the terminal one by one. Remember to hit the Enter key after each of these commands.
3. Once these commands are executed successfully, close all the apps and restart your machine.
4. Now, try to connect with your email client and check if this resolves the email blocked error.
If not, let’s move to the next solution.
3. Request Addition To Whitelist
This concerns the anti-spam filter leading to the glitch in your recipient’s inbox. The only fix to this cause is to connect with the concerned party. You’ll have to manually ask them or the recipient to update their spam filtering in the spam rules tab.
Once you are done with these updates, try replicating the steps and check if you get a similar message. However, if that doesn’t turn the tide, move ahead to look at the next one.
4. Update Exchange Email Settings
Microsoft 365 is a suite of applications made available to every employee of an organization. Hence, if you or your recipient’s address relates to an organization that uses this suite, this section can help you.
Let’s get started with the basics. DBEB is a default setting offered by Microsoft 365 and is instructed to block external emails. It can distinguish email addresses as external or internal by referring to the Azure Active Directory.
So if any email addresses are stored in the public folder mailbox, they are treated as external. Although they might be valid, you’ll have to take extra steps to remove the rejection error code.
Follow the steps below to apply the fix per your public server hosting scenario.
1. For On-premise public servers hosting
Under this, we’ll take the necessary steps to update the Optional Features of the Microsoft Azure Active Directory Connect screen. Doing this will mark the public folder mailbox as valid for the DBED. The steps are:
1. Open the Microsoft Azure Active Directory Connect screen for your account.
2. Click on the ‘Optional Features’ option on the left menu. This will open the permissions under this section.
3. Check the Exchange Mail Public Folder by checking the check box.
4. Save the changes, which should resolve the email unknown recipient issue.
2. For public servers hosted in Exchange Online
As of now, DBEB has limitations to hosting public servers in Exchange online. However, we have a workaround to achieve it for the Mail Enabled Public Folders.
Under this workaround, you’ll update the Mail flow so that the emails addressed to the public folder no longer go through the Exclaimer Cloud.
Let’s understand the following the steps to do so:
1. Log in to Exchange Online.
2. Navigate to the Mail Flow option and click on ‘Rules.’ This will open many rules in the exchange.
3. Look for ‘Identify Messages to send to Exclaimer Cloud’ and click the edit button.
4. Click on ‘Add Exception,’ and select recipient, followed by the ‘is this person’ option.
5. Select all public folder mailboxes under the ‘select member’s dialogue.’
6. Lastly, click Add and then Ok for the changes to take effect.
A bonus tip
Another workaround to hosting public servers in Exchange online is entirely disabling the DBEB. While this may seem a solution, except it is not. This removes all email and IP filtering to prevent any email-based security attacks. Therefore, you are advised not to disable the DBEB feature in Microsoft 365.