I verified and tested the DNS settings as correct. Then I ran the inbound SMTP email test and all the steps passed except for the final one:
Attempting to send a test email message to PII masked by moderator using MXPII masked by moderator.mail.protection.outlook.com.
Delivery of the test email message failed.
Additional Details
The server returned status code 550 - Mailbox unavailable. The server response was: 5.7.1 Service unavailable, Client host [40.69.150.142] blocked using Spamhaus. To request removal from this list see http://www.spamhaus.org/lookup.lasso
(AS16012611) [BL2NAM02FT050.eop-nam02.prod.protection.outlook.com]
Exception details:
Message: Mailbox unavailable. The server response was: 5.7.1 Service unavailable, Client host [40.69.150.142] blocked using Spamhaus. To request removal from this list see http://www.spamhaus.org/lookup.lasso (AS16012611) [BL2NAM02FT050.eop-nam02.prod.protection.outlook.com]
Type: System.Net.Mail.SmtpFailedRecipientException
Stack trace:
at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at Microsoft.Exchange.Tools.ExRca.Tests.SmtpMessageTest.PerformTestReally()
Elapsed Time: 5411 ms.
The full text of the inbound SMTP test results:
Testing inbound SMTP mail flow for domain 'PII masked by moderator'.
The Microsoft Connectivity Analyzer failed to test inbound SMTP mail flow.
Additional Details
Elapsed Time: 6996 ms.
Test Steps
Attempting to retrieve DNS MX records for domain 'PII masked by moderator'.
One or more MX records were successfully retrieved from DNS.
Additional Details
MX Records Host
PII masked by moderator.mail.protection.outlook.com, Preference 0
Elapsed Time: 602 ms.
Testing Mail Exchanger
PII masked by moderator.mail.protection.outlook.com.
One or more SMTP tests failed for this Mail Exchanger.
Additional Details
Elapsed Time: 6393 ms.
Test Steps
Attempting to resolve the host namePII masked by moderator.mail.protection.outlook.com in DNS.
The host name resolved successfully.
Additional Details
Testing TCP port 25 on host
PII masked by moderator.mail.protection.outlook.com to ensure it's listening and open.
The port was opened successfully.
Additional Details
Analyzing SMTP Capabilities for server
PII masked by moderator.mail.protection.outlook.com:25
SMTP Capabilities were analyzed successfuly.
Additional Details
Attempting to send a test email message to *** Email address is removed for privacy *** using MXPII masked by moderator.mail.protection.outlook.com.
Delivery of the test email message failed.
Additional Details
The server returned status code 550 - Mailbox unavailable. The server response was: 5.7.1 Service unavailable, Client host [40.69.150.142] blocked using Spamhaus. To request removal from this list see http://www.spamhaus.org/lookup.lasso
(AS16012611) [BL2NAM02FT050.eop-nam02.prod.protection.outlook.com]
Exception details:
Message: Mailbox unavailable. The server response was: 5.7.1 Service unavailable, Client host [40.69.150.142] blocked using Spamhaus. To request removal from this list see http://www.spamhaus.org/lookup.lasso (AS16012611) [BL2NAM02FT050.eop-nam02.prod.protection.outlook.com]
Type: System.Net.Mail.SmtpFailedRecipientException
Stack trace:
at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at Microsoft.Exchange.Tools.ExRca.Tests.SmtpMessageTest.PerformTestReally()
Elapsed Time: 5411 ms.
***Post moved by the moderator to the appropriate forum category.***