Email issues after adding new domain

[caperson1976]

I'm still pretty new to the Microsoft 365 Admin Center and I was wondering if anyone has had an issue where they add a new domain for a company that was already using 365 but they changed their name and wanted a new domain to go with the name change. I run a small independent IT shop and I am receiving reports from my customers that when they send out emails to their clients, the clients are reporting that they never received any email. The clients have also checked their spam folders to make sure it didn't end up there, to no avail. Before changing over to the new domain and email address this was not an issue.

Ideas?

Thank you in advance.

[#2 · Accepted solution]

Best run some message traces, they should give you a clue as to what's happening: https://docs.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/message-trace-modern-eac
Also, make sure that you have configured SPF for your domain as a minimum, and preferably DKIM/DMARC as well. https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/set-up-spf-in-office-365...

[#3]

@VasilMichev These are the most common NDRs that I found...

550 5.4.316 Message expired, connection refused, Socket error code 10061‎

‎554 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137‎

550 5.1.0 550 #5.1.0 Address rejected‎

I have looked each one of these up and they all appear to be a recipient side issue, whereas the recipient's "IT" needs to add our email address(es) or domain to their allow/white list. These issues were not happening with the initial domain that was setup. I added the new domain directly through the M 365 Admin Center and all required DNS Records were created automatically and are showing as Healthy or OK. The only good thing here is that it's not happening for every client, only just a select few at this time.

Any additional ideas/thoughts on this matter?

Thank you in advance.

[#4]

@VasilMichev 

Thanks for your response. I did run traces before, but I ran them again so I could pull the errors I am seeing. These are the common errors...

550 5.4.316 Message expired, connection refused, Socket error code 10061‎

‎554 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137‎

550 5.1.0 550 #5.1.0 Address rejected‎

They all lead me to believe the issue is in fact on the recipients side but i'm not sure WHY these emails are being flagged. When I created the new domain, I did it directly from within the 365 Admin Center and it is currently showing that everything is good to go (Healthy or OK). Not sure what else to check after this.

Additional ideas/thoughts?

[#5]

Check SPF/DKIM/DMARC records as per the article above and the references therein.

[#6]

Have you confirmed the new domain name is in the list of accepted domains in Exchange Online

[#7]

I think the DKIM did the trick. I have not received any further reports of NDRs. Thank you so much for the nudge in the right direction.