Fix email delivery issues for error code 550 5.1.1 through 5.1.20 in Exchange Online (2023)

  • Article
  • 8 minutes to read

Important

Mail flow rules are now available in the new Exchange admin center. Try it now!

It's frustrating when you get an error after sending an email message. This article describes what you can do if you see error codes 550 5.1.1 through 5.1.20 in a non-delivery report (also known as an NDR, bounce message, delivery status notification, or DSN).

Fix email delivery issues for error code 550 5.1.1 through 5.1.20 in Exchange Online (1)I got this bounce message. How do I fix it?Fix email delivery issues for error code 550 5.1.1 through 5.1.20 in Exchange Online (2)I'm an email admin. What can I do to fix this?

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

Here are some steps that you can try to fix the problem yourself.

If the steps in this section don't fix the problem for you, contact your email admin and refer them to the information in this article so they can try to resolve the issue for you.

Solution 1: Confirm the recipient's email address

It sounds too simple, but the wrong email address is the most common issue that causes 5.1.x errors. Check for correct spelling and send the message again if you find an error in the email address.

To resend the message in Outlook, see Resend an email message.

Solution 2: Remove the recipient's email address from your Auto-Complete list

You might have an invalid entry in your Auto-Complete list (also known as the nickname cache) for the recipient. For example, the recipient might have been moved from an on-premises Exchange organization to Exchange Online, or vice-versa. Although the recipient's email address is the same, other internal identifiers for the recipient might have changed, thus breaking your cached entry for the recipient.

Fix your Auto-Complete list entries in Outlook

To remove invalid recipients or all recipients from your Auto-Complete list in Outlook 2010 later, see Manage suggested recipients in the To, Cc, and Bcc boxes with Auto-Complete.

Fix your Auto-Complete list entries in Outlook on the web

To remove recipients from your Auto-Complete list in Outlook on the web (formerly known as Outlook Web App), do one of the following procedures:

(Video) Email Undeliverable | Error code 5.1.10 in Office 365 | Update accepted domain settings | Exchange

Remove a single recipient from your Outlook on the web Auto-Complete list
  1. In Outlook on the web, click New mail.

  2. Start typing the recipient's name or email address in the To field until the recipient appears in the drop-down list.

    Fix email delivery issues for error code 550 5.1.1 through 5.1.20 in Exchange Online (3)

  3. Use the Down Arrow and Up Arrow keys to select the recipient, and then press the Delete key.

Remove all recipients from your Outlook on the web Auto-Complete list**

You can only clear your Auto-Complete list in the light version of Outlook on the web. To open your mailbox in the light version of Outlook on the web, do either of the following steps:

  • Open the mailbox in an older web browser that only supports the light version of Outlook on the web (for example, Internet Explorer 9).

  • Configure your Outlook on the web settings to only use the light version of Outlook on the web (the change takes effect the next time you open the mailbox):

    1. In Outlook on the web, click Settings Fix email delivery issues for error code 550 5.1.1 through 5.1.20 in Exchange Online (4).

    2. In the Search all settings box, type light and select Outlook on the web version in the results.

    3. In the page that opens, select Use the light version of Outlook on the web, and then click Save.

    4. Log off, close your web browser, and open the mailbox again in Outlook on the web.

After you open your mailbox in the light version of Outlook on the web, do the following steps to clear all entries from your Auto-Complete list:

  1. Choose Options and verify that Messaging is selected.

    (Video) 550 Authentication - Undeliverable email

  2. In the E-Mail Name Resolution section, click Clear Most Recent Recipients list, and then click OK in the confirmation dialog box.

  3. While you're still in Options, to return your mailbox to the full version of Outlook on the web, go to Outlook version, clear the check box for Use the light version, and then click Save.

  4. Log off and close your web browser. The next time you open your mailbox in a supported web browser, you'll use the full version of Outlook on the web.

To remove invalid recipients or all recipients from your Auto-Complete list in Outlook 2010 later, see Manage suggested recipients in the To, Cc, and Bcc boxes with Auto-Complete.

Solution 3: Confirm that the recipient isn't auto-forwarding messages from you to another (and likely, invalid) email address

Does the recipient's email address in your original message exactly match the recipient's email address in the NDR? Compare the recipient's email address in the NDR with the recipient's email address in the message in your Sent Items folder.

If the addresses don't match, contact the recipient (by phone, in person, etc.) and ask them if they've configured an email rule that forwards incoming email messages from you to another destination. Their rule could have tried to send a copy of your message to a bad email address. If the recipient has such a rule, they'll need to correct the destination email address or remove the rule in order to prevent 5.1.x message delivery errors.

Solution 4: Verify that your account hasn't been compromised

Did you send the original message at all? If not, it's possible that a spammer or hacker inappropriately used your account to send the message.

Check your recent messages in the Sent Items folder for strange or unknown messages (messages that you didn't send). If you find any, it's possible that your email account was compromised.

If you believe that your account has been compromised, follow these steps:

  • Reset your password and scan your devices for malware. However, the hacker might have configured other settings on your mailbox (for example, created Inbox rules to auto-forward email messages or added additional mailbox delegates). So, follow the additional steps in How to determine whether your account has been compromised.

  • Notify your email admin. Your admin will need to unblock your account before you can send email again.

Solution 5: Confirm that the NDR is related to a message that you actually sent

If your Sent folder contains only messages that you know you sent, then the NDR you received could be a result of backscatter (a useless NDR about a message you didn't send), and you can ignore it.

Typically, if a message can't be delivered, the recipient's email system will use the sender's email address in the From field to notify the sender in an NDR like this one. But what if the message was sent by a spammer who falsified the From address so it appears the message came from your email address? The resulting NDR that you'll receive is useless because it creates the false impression that you did something wrong. This type of useless NDR is called backscatter. It's annoying, but if this NDR is backscatter, your account hasn't been compromised.

(Video) Office 365 Email delivery issues

Check your recent messages in the Sent Items folder for strange or unknown messages (messages that you didn't send). If you don't see any suspicious messages, it's likely that the NDR you received is backscatter. If you've already changed your password and run an anti-malware scan, you can ignore these backscatter NDRs.

To learn more, see Backscatter in EOP.

I'm an email admin. What can I do to fix this?

If the steps in the previous section don't solve the issue for the sender, the solution might be related to the way the user's Microsoft 365 or Office 365 account is set up. If you have a hybrid topology, the solution might also be related to the on-premises mail transfer agent. It might also be a problem with the recipient's domain configuration. Here are four solutions you can try. You might not need to try all of them to get the message sent successfully.

Solution 1: Check the Microsoft 365 admin center for configuration problems or service-wide issues

For Microsoft 365 or Office 365 accounts, the Microsoft 365 admin center provides a central source for various tools, notifications, and information that you can use to troubleshoot this and other issues.

Open the Microsoft 365 admin center, and from the Home page, do the following items:

  1. Check the Message Center to see if your organization has a known configuration issue.

  2. Go to Health > Service health to see if there's a current service issue in Microsoft 365 or Office 365 affecting the user's account.

  3. Check the sender and recipient domains for incorrect or stale mail exchange (MX) resource records by running the Mailflow Troubleshooter tool that is available within Microsoft 365 and Office 365.

If there's a problem with the recipient's domain, contact the recipient or the recipient's email administrator to let them know about the problem. They'll have to resolve the issue in order to prevent NDR 5.1.x errors.

Solution 2: Update stale MX records

Error code 5.1.1 can be caused by problems with the MX resource record for the recipient's domain. For example, the MX record might point to an old email server, or the MX record might be ambiguous due to a recent configuration change.

Note

Updates to a domain's DNS records can take up to 72 hours to propagate to all DNS servers on the Internet.

(Video) Fix: The server responded 550 error on Outlook email app

If external senders (senders outside your organization) receive this NDR when they send message to recipients in your domain, try the following steps:

  • The MX resource record for your domain might be incorrect. The MX record for an Exchange Online domain points to the email server (host) <domain>.mail.protection.outlook.com.

  • Verify that you have only one MX record configured for your Exchange Online domain. We don't support using more than one MX record for domains enrolled in Exchange Online.

  • Test your MX record and your ability to send email from your Exchange Online organization by using the Verify MX Record and Outbound Connector Test at Office 365 > Mail Flow Configuration in the Microsoft Remote Connectivity Analyzer.

For more information, see Add DNS records to connect your domain and Set up SPF to help prevent spoofing.

Solution 3: Update forwarding rules to remove incorrect email addresses

This NDR might be caused by a forwarded (unintended) recipient that's configured for the intended recipient. For example:

  • A forwarding Inbox rule or delegate that the recipient configured in their own mailbox.

  • A mail flow rule (also known as a transport rule) configured by an email admin that copies or forwards messages sent to the recipient to another invalid recipient.

For more information, see Configure email forwarding for a mailbox.

Still need help with error code 5.1.1 to 5.1.20?

See also

Email non-delivery reports in Office 365

(Video) DevOps & SysAdmins: Getting a [550 5.1.1 Recipient not found] (Can't receive email) with CloudFlare

FAQs

How do I fix error 550 5.1 1? ›

Solution 1: Confirm the recipient's email address

It sounds too simple, but the wrong email address is the most common issue that causes 5.1. x errors. Check for correct spelling and send the message again if you find an error in the email address. To resend the message in Outlook, see Resend an email message.

How do I fix error 550 on my email? ›

How do I fix a 550 error?
  1. Check for email address typos. ...
  2. Check whether the email IP is blacklisted. ...
  3. Try sending the email after some time. ...
  4. Try changing your outgoing mail port. ...
  5. Check whether IP filtering is enabled. ...
  6. Enable SMTP authentication. ...
  7. Troubleshoot the SSL method. ...
  8. Contact your ISP.
May 19, 2020

How to fix 550 5.1 8? ›

Go to the Restricted users page in the Microsoft 365 Defender portal at https://security.microsoft.com/restrictedusers to unblock the account. After you unblock the account, the user should be able to resume sending messages within a few hours.

What does it mean when it says recipient address rejected Access denied? ›

As mentioned earlier, some “Recipient Address Rejected: access denied” errors are associated with the Directory-Based Edge Blocking (DBEB) option. This glitch happens when you configure your Email with Exclaimer Cloud through Microsoft 365 since this is known to cause external emails to be rejected.

How to fix 550 permanent failure for one or more recipients? ›

Server IP Blacklisted by Recipient's Mail Server

So, if you get a “550 permanent failure for one or more recipients” error, the first thing you have to do is to confirm whether your server IP has been blacklisted or not. Moreover, there are lots of tools available that can help you with spam blacklist checks.

How do I fix SMTP error from remote mail server? ›

Solution - Here's How To Resolve It
  1. Ensure the configuration does not have any errors.
  2. Ensure that the sender's domain is not present within any blocklist.
  3. Ensure that the recipient's email account is active and is capable of receiving emails.
  4. Ensure that the SMTP server contains the correct MX records.

How do you fix 550 permanent failure? ›

If the problem is in validity of the recipient address - you will get "550 5.1. 1: Recipient address rejected". To solve this you just need to check if the address you are sending an email is existent and typed correctly.

How do I enable SMTP authentication? ›

Enable SMTP AUTH for specific mailboxes
  1. Open the Microsoft 365 admin center and go to Users > Active users.
  2. Select the user, and in the flyout that appears, click Mail.
  3. In the Email apps section, click Manage email apps.
  4. Verify the Authenticated SMTP setting: unchecked = disabled, checked = enabled.
Sep 28, 2022

Could not be delivered because of 550 5.4 1 Recipient address rejected Access denied? ›

You received this error message because of the Directory-Based Edge Blocking (DBEB). By default, the DBEB is enabled for your domains in Microsoft 365 and will reject external emails with addresses that are not present within the Azure Active Directory.

Why am I not recognized as a valid sender? ›

Your message couldn't be delivered because you weren't recognized as a valid sender. The most common reason for this is that your email address is suspected of sending spam and it's no longer allowed to send messages outside of your organization. Other alternatives are UT Lists or EMMA, depending on your use-case.

How do you check if an email is being blocked in Office 365? ›

Go to https://protection.office.com/#/quarantine.
  1. Click Threat management and then click Review.
  2. Click Quarantine (any where in the box). A list of your emails in quarantine are displayed.
  3. Click any message to select it, then choose from the options given: Release message. View message header. Preview message.

What does 550 rejected by header based manually blocked senders mean? ›

550. Rejected by header-based Blocked Senders - Block policy for Header From. A Block Sender Policy has been applied to reject emails based on the Header From or Envelope From address. Delete or change the Blocked Senders policy.

What is 550 5.1 1? ›

550 5.1. 1 means that the recipient email server believes that the email address does not exist at the destination domain, and therefore has no way to deliver it. Unless you simply made a typo in the email address, this is not something that you can fix, and must be addressed at the other end.

Why am I getting this your message wasn't delivered because the recipient's email provider rejected it? ›

This error message indicates that the message was filtered and rejected as it got a very high spam score. If the message was legitimate, contact Support and provide them with the full bounce back message (including the Diagnostic information for administrators section).

Why would my email address be rejected by the server? ›

When you send an email and get an “address rejected” error message, it means the email server can't verify your email address because the SMTP server authentication feature is disabled in your email client.

Has blocked this email because the sender IP 550 address is blacklisted? ›

This means that the receiving mail server did not accept your message because the IP address of the sender is on a blacklist (usually due to spamming abuse). This can be either your IP address or the IP address of the mail environment that hosts your mailbox.

How do you fix too many recipients in Outlook? ›

Working with and around the limitations

For the first limitation, you can use a Mail Merge. For the second limitation, you can use a mail merge add-in which automatically breaks the mail merge into batches which are each below this limit. Several of these tools are also discussed in the Mail Merge guide.

What does 550 permanent failure for one or more recipients mean? ›

What causes 550 permanent SMTP errors? The IP address of the sender's server is blacklisted in the receiver's mail hosting server. The email address of the recipient does not exist or is not found. In case of the recipient's mail inbox is full and there is not enough space to receive any more mails.

How do I turn off SMTP restrictions? ›

Procedure
  1. Login to WHM as the root user.
  2. Navigate to: "Home »Security Center »SMTP Restrictions."
  3. Click the "Disable" button.
Aug 1, 2022

How to solve Outlook cannot connect to your outgoing SMTP email server? ›

Possible Solution:
  1. Please verify that you have enabled "My SMTP Requires Authentication" in Incoming mail server Outlook settings.
  2. If this does not work out, then try to disable the firewall of your local machine from where you are trying to send out an email.

How do I fix email not connecting to server? ›

Cannot send emails: How to fix email sending issues
  1. Check your internet connection. Yup. ...
  2. Check your SMTP server details. ...
  3. Verify all usernames and passwords. ...
  4. Check your SMTP server connection. ...
  5. Change your SMTP port. ...
  6. Control your antivirus or firewall settings.

Is My email address blacklisted? ›

Because there are more than a hundred blacklists out there, your best bet is to use an aggregate service like MXToolBox to find out if your email address has made its way onto the dark side. Other helpful tools that you might want to try include the Barracuda Reputation Block List, MultiRBL, and Sender Score.

What is 550 Verification failed? ›

If you encounter a "550 unable to verify sender address" error when trying to send an email, it indicates that the MX (incoming) mail server of your sender email address is either not responding, or is non-existent.

What does server error 550 relay not permitted mean? ›

When a user receives a 550 relay not permitted error, it means they are not permitted to send an email via the server that they are attempting to send an email from. When users send an email from their Internet Service Providers (ISP) mail servers, they generally do not have to authenticate themselves.

How do I bypass SMTP authentication? ›

The solution is to add the IP addresses of these servers/sites to SmarterMail's whitelist, and whitelist the IP or IP block for SMTP Authentication Bypass. Adding an IP to the SMTP Auth Bypass whitelist means that the IP address, or IP block, will not be asked to provide an SMTP Authentication login.

How do I check my SMTP authentication? ›

To test SMTP authentication via telnet, complete the following steps:
  1. Open the terminal and connect with the mail server using the telnet server name and access command — mail.port25.com in the example above.
  2. Greet the server with EHLO or HELO, enter AUTH LOGIN, and wait for the computer's response.
Feb 7, 2020

How do I know if my SMTP credentials are working? ›

To test SMTP authentication via telnet:
  1. In a telnet client such as PuTTY, connect to the SMG appliance: telnet <SMG_IP_address> 587.
  2. Greet the mail server: EHLO mailserver.com.
  3. Tell SMG you want to authenticate with it: AUTH LOGIN. ...
  4. Paste the base64 encoded username. ...
  5. Paste the base64 encoded password for the username.
Apr 1, 2019

Why was my email message blocked? ›

You may receive this automatic reply after sending an email. This message tells you that your email wasn't sent to the intended recipient because the spam filter thinks it is a spam email.

How do you fix you don't have permission to send messages from this mailbox? ›

Outlook Web Mail Error "You don't have permission to send messages from this mailbox".
  1. click the setting-gear in top right corner.
  2. click full settings.
  3. goto 'sync email'
  4. there you have the possibility to "Set default from address"
  5. here I can change it to my address associated with my microsoft acccount.
Apr 30, 2018

How to fix 550 5.4 1? ›

Check your domain status in the Microsoft 365 admin center.
  1. Log in to the Microsoft 365 admin center.
  2. From the left-hand menu, select domains and ensure the domain is listed as active.
  3. Now go to Admin and select the Exchange admin center.
  4. Click on Mail flow, then Accepted domains.

Why does it keep saying enter a valid email address? ›

This error often occurs when trying to enter an address with a prefix like support@ or help@ , which are not allowed. The email address you should be entering at this stage is an address that is unique to you, as this will be the address that you use to log into your account.

How do I unblock an email address in exchange? ›

Unblock office email accounts
  1. Log into your Microsoft 365 Admin console to unblock office email accounts.
  2. In the Exchange admin center (EAC), navigate to protection > action center.
  3. Find the blocked user and select unblock account.
  4. Click Yes to confirm the change.
Aug 9, 2017

How do I authenticate an email sender? ›

How to Authenticate Your Email in 5 Steps
  1. Use consistent sender addresses. Be consistent with the from addresses and friendly from names you use. ...
  2. Authenticate your IP addresses with SPF. ...
  3. Configure DKIM signatures for your messages. ...
  4. Protect your domain with DMARC authentication. ...
  5. Prepare for BIMI.
Feb 22, 2021

How do you check if emails are being blocked Exchange? ›

The only way to find out if you're blocked is by checking your email server log files (see next section), or waiting until your users or recipients complain. Microsoft Hosted Exchange and 'Bigfish.com'.

How do I know if Exchange Online is blocking emails? ›

To get there, do the following:
  1. Sign in to Office 365 with an admin credential.
  2. Select the app launcher icon in the upper-left and choose Admin.
  3. Go to Exchange.
  4. Under mail flow, go to message trace. For more details about message trace, please refer to Run a Message Trace and View Results.
Jan 28, 2017

Why is Office 365 blocking emails? ›

Microsoft 365 puts a block on sending “bulk email” because if your computer or your email account is compromised the criminals are likely to try to email all your contacts. They may also try to use your compromised account to spam a huge email list of their own.

How do you fix this error message 550 5.1 1 User unknown? ›

If the recipient doesn't have the email address that you're sending to, it will bounce the mail with the error message '550 5.1. 1 User unknown'. Solution: Always validate the recipient email address you've given in the email for any spelling mistakes or errors.

How to solve 550 5.7 1 unsolicited mail? ›

550, "5.7. 1", The IP you're using to send mail is not authorized to send email directly to our servers. Please use the SMTP relay at your service provider instead. For more information, visit 'The IP you're using to send email is not authorized...'.

How do I fix error 550 5.7 1? ›

Remove the sender restriction: Change your group settings to unblock the sender in one of the following ways:
  1. Add the sender to the group's allowed senders list. ...
  2. If the sender is restricted because they're external (outside your organization), configure the group to accept messages from external senders.
Sep 11, 2022

What does this mean 550 5.4 1 Recipient address rejected Access denied? ›

Why did I get this bounce message? The email server that's generating the error doesn't accept email from the sender's domain (for example, @fabrikam.com). This error is generally caused by email server or DNS misconfiguration.

Why does my email say the server rejected one of the recipients addresses? ›

When you send an email and get an “address rejected” error message, it means the email server can't verify your email address because the SMTP server authentication feature is disabled in your email client.

What is a 550 permanent failure? ›

What causes 550 permanent SMTP errors? The IP address of the sender's server is blacklisted in the receiver's mail hosting server. The email address of the recipient does not exist or is not found. In case of the recipient's mail inbox is full and there is not enough space to receive any more mails.

How do you fix Outlook your message wasn't delivered because the recipient's email provider rejected it? ›

7 answers
  1. Expand Threat Management and click Policy.
  2. Click Anti Spam.
  3. In the Anti-Spam settings, locate Outbound policy and click Edit protection settings.
  4. In the Outbound policy, expand Automatic forwarding rules. The default is set to Automatic – System-controlled.
  5. Select On – Forwarding is enabled and click Save.
Feb 22, 2022

Why am I suddenly getting access denied? ›

The “Access Denied” error appears when your browser uses different proxy settings or VPN instead of what's really set on your Windows 10 PC. Thus, when a website detects that there is something wrong with your browser cookies or your network, it blocks you and this is why you can't open it.

How do I bypass Access Denied system error 5? ›

Fix System Error 5 on Standard Windows Accounts
  1. Sign in to your administrator account and select Start > Settings > Accounts > Family & other users.
  2. Select the standard account under Other users and select Change account type.
  3. Set Account type to Administrator and select OK.
Feb 3, 2022

What is 550 5.1 0 address rejected? ›

The destination email server that generated the 5.1. 0 error won't accept messages from you (the sender) or messages for the recipient. This can happen if messages from you (your email address, your Exchange Online organization, or even all of Exchange Online) are being blocked by the recipient.

Videos

1. DevOps & SysAdmins: 550 5.1.1 relay denied NDR Error (2 Solutions!!)
(Roel Van de Paar)
2. Solución error 554 5.7.1 al enviar emails fácilmente desde nuestro servidor vps en español
(Redes Binarias)
3. DevOps & SysAdmins: NDR "550 5.1.1 Resolver.adr.ExRecipNotFound" after exchange migration
(Roel Van de Paar)
4. Undeliverable: 修正 Exchange Online 中錯誤碼為 550 5.1.1 到 5.1.20 的電子郵件傳遞問題 【找不到地址】收件者:61527837@gmail.com
(信箱換鎖佬 WT)
5. SMTP server error: 5.7.1 : Recipient address rejected: Access denied
(Paul Heffner)
6. Fix Email Error 550 when sending email using Outlook/Mail w/ Norton installed
(HalfGēk)
Top Articles
Latest Posts
Article information

Author: Dean Jakubowski Ret

Last Updated: 03/19/2023

Views: 5717

Rating: 5 / 5 (50 voted)

Reviews: 81% of readers found this page helpful

Author information

Name: Dean Jakubowski Ret

Birthday: 1996-05-10

Address: Apt. 425 4346 Santiago Islands, Shariside, AK 38830-1874

Phone: +96313309894162

Job: Legacy Sales Designer

Hobby: Baseball, Wood carving, Candle making, Jigsaw puzzles, Lacemaking, Parkour, Drawing

Introduction: My name is Dean Jakubowski Ret, I am a enthusiastic, friendly, homely, handsome, zealous, brainy, elegant person who loves writing and wants to share my knowledge and understanding with you.