Solved: How do I fix Outlook Mail Undeliverable 550 Access Denied Error?

Problem: Emails sent from an email client such as Microsoft Outlook or Outlook Express, show the result in an error and the email is undeliverable.

The detailed error message as below:

Undeliverable: 500 error
System Administrator
Your message did not reach some or all of the intended recipients.
550 relay not permitted

550 relay not permitted
550 relay not permitted

Your message did not reach some or all of the intended recipients.
550 Message rejected because XXX is blacklisted.

550 Message rejected because XXX is blacklisted.
550 Message rejected because XXX is blacklisted.

Task XXX – Sending reported error (0x800CCC78): ‘Cannot send the message. Verify the e-mail address in your account properties. The server responded: 550 Access denied – Invalid HELO name (See RFC2821 4.1.1.1)’

Task XXX - Sending reported error (0x800CCC78): 'Cannot send the message. Verify the e-mail address in your account properties. The server responded: 550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)'
Task XXX – Sending reported error (0x800CCC78): ‘Cannot send the message. Verify the e-mail address in your account properties. The server responded: 550 Access denied – Invalid HELO name (See RFC2821 4.1.1.1)’

Some errors occurred while processing the tests. Review the list of errors below for more details. If the problem persist after taking the suggested actions, contact your Internet Service provider.
Send test email message: The server responded: 550 SMTP AUTH is required

Some errors occurred while processing the tests. Review the list of errors below for more details. If the problem persist after taking the suggested actions, contact your Internet Service provider.  Send test email message: The server responded: 550 SMTP AUTH is required
Some errors occurred while processing the tests. Review the list of errors below for more details. If the problem persist after taking the suggested actions, contact your Internet Service provider. Send test email message: The server responded: 550 SMTP AUTH is required

Undeliverable: TEST
System Administrator
Your message did not reach some or all of the intended recipients.
Server error: ‘550 5.7.1 Unable to relay’

Undeliverable: TEST System Administrator Your message did not reach some or all of the intended recipients. Server error: '550 5.7.1 Unable to relay'
Undeliverable: TEST System Administrator Your message did not reach some or all of the intended recipients. Server error: ‘550 5.7.1 Unable to relay’

Your message did not reach some or all of the intended recipients.
550 5.7.1 Client does not have permissions to send as this sender

Your message did not reach some or all of the intended recipients. 550 5.7.1 Client does not have permissions to send as this sender
Your message did not reach some or all of the intended recipients. 550 5.7.1 Client does not have permissions to send as this sender

550 5.7.1 Unfortunately, messages from XXX weren’t sent. Please contact your Internet service provider since part of their network is on our block list (S3150).

550 5.7.1 Unfortunately, messages from XXX weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150).
550 5.7.1 Unfortunately, messages from XXX weren’t sent. Please contact your Internet service provider since part of their network is on our block list (S3150).

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.
SMTP error from remote mail server after end of data: 550 5.7.64 Relay Access Denied ATTR36.

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. SMTP error from remote mail server after end of data: 550 5.7.64 Relay Access Denied ATTR36.
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. SMTP error from remote mail server after end of data: 550 5.7.64 Relay Access Denied ATTR36.

Task XXX: ‘The connection to the server was interrupted. If the problem continues, contact your server administrator or Internet server provider (ISP). The server responded: 550 5.1.0 ESMTP server not available AUP#O-1070’

Task XXX: 'The connection to the server was interrupted. If the problem continues, contact your server administrator or Internet server provider (ISP). The server responded: 550 5.1.0 ESMTP server not available AUP#O-1070'
Task XXX: ‘The connection to the server was interrupted. If the problem continues, contact your server administrator or Internet server provider (ISP). The server responded: 550 5.1.0 ESMTP server not available AUP#O-1070’

Remote Server returned ‘550 5.7.501 Service unavailable. Banned Sender.’

Remote Server returned '550 5.7.501 Service unavailable. Banned Sender.'
Remote Server returned ‘550 5.7.501 Service unavailable. Banned Sender.’

Your message to XXX couldn’t be delivered.
When Office 365 tried to send your message, the receiving email server outside Office 365 reported an error.
Reported error: 550 5.0.350 Remote server returned an error -> 550 Serner frequency limited.

Your message to XXX couldn't be delivered. When Office 365 tried to send your message, the receiving email server outside Office 365 reported an error. Reported error: 550 5.0.350 Remote server returned an error -> 550 Serner frequency limited.
Your message to XXX couldn’t be delivered. When Office 365 tried to send your message, the receiving email server outside Office 365 reported an error. Reported error: 550 5.0.350 Remote server returned an error -> 550 Serner frequency limited.

Follow the below solution steps to resolve the Outlook email undeliverable 500 access denied issue.

Content Summary

Solution 1: Verify Recipient Email
Solution 2: Verify SMTP settings
Solution 3: Disable Antivirus and Firewall Temporarily
Solution 4: Disable Outlook Add-ins
Solution 5: Check Data Integrity
Solution 6: Contact Administrator
Here are a few things you need to check, follow the below process one by one:

Solution 1: Verify Recipient Email

Cross-check the recipient’s email address to verify if it is correct. If not, insert the correct address and try sending the email again.

Solution 2: Verify SMTP settings

Check your email account settings including the SMTP server is correct or not. If not then correct it. Below are the steps to configure SMTP Authentication in Microsoft Outlook 2010 for Windows:

Step 1: Go to File > Info > Account Settings.

Step 2: Select your email address from the list of accounts and click Change.

Step 3: Click on More Settings…. > Outgoing Server tab.

Step 4: Check the box next to My outgoing server (SMTP) requires authentication and ensure the Use same settings as my incoming mail server is selected.

Step 5: Click OK then Next.

Step 6: Click Finish.

Solution 3: Disable Antivirus and Firewall Temporarily

Malware and virus infection can also be the cause for error 550, So check and resolve it. Or you can try to disable virus scanner integration and firewall settings temporarily to check and verify.

Solution 4: Disable Outlook Add-ins

Issues with Outlook add-ins. Below steps show you how to disable or remove add-ins:

Step 1: Go to File > Options > Add-ins.

Step 2: At the bottom of the window, where it says Manage, click the Go button.

Step 3: Select the add-ins you want to disable or remove. To disable the add-in, uncheck the box in front of its name. To uninstall the add-in select it and click Remove.

Step 4:  Click OK to save your changes and return to your document.

Solution 5: Check Data Integrity

Problems associated with abrupt termination can be fixed by opening Outlook in safe mode. The following are the steps to open Outlook in safe mode.

Step 1: Press Crtl + R to open the Run box.

Step 2: Type, “outlook /safe” and press Enter.

Solution 6: Contact Administrator

When the junk email volumes increase, network administrators (the people who are responsible for managing ISP servers) will place restrictions on SMTP email servers to prevent spam on their network. If this is the reason, contact your ISP administrator to resolve the issue.