Office 365 Migrated mailboxes not receiving External mail

After setting up Exchange Online (Office 365) with Exchange 2010 SP3 Hybrid, my migrated remote mailboxes will not receive external email. They can receive email from other Online, cloud users. All the mailboxes created in Office 365 can receive external email. In doing a mail trace, -EventID 'DSN' the Source shows 'Routing'. I eventually get 'Delivery is Delayed' message. Any thoughts?
Anthony K O365Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Vasil Michev (MVP)Commented:
Where is you MX pointing at? If it points on-prem, check if they receive emails from on-prem users - if not, the issue is with the connector, most likely the certificate.

Also, try sending directly to the address.
Anthony K O365Author Commented:
MX record is point to our On prem Exchange. Migrated users (Online) can not receive email from On Prem senders nor Internet senders. However, they can receive email when using their address.

You stated the issue may be with the connector. Do you mean the Receive connector at Exchange Online, or the Sender Connector On Prem? The settings for Inbound connector at O365 is: Sender Domain=*, Security=Require TLS=No, Sender IP= same IP being used for (therefore, no certificate required) We are using Wild Card Certs On prem. Must it also be used Online?
Vasil Michev (MVP)Commented:
OK, definitely an issue with the connector then. Have you traced the email from both on-prem and EO? Post the results here and also any NDRs you might have gotten. Also, the connector settings (you can even rerun the HCW to recreate them, which might as well fix the issue).

Just in case, also double-check the targetaddress attribute for any of the migrated mailboxes, it might not be correctly populated.
Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

Anthony K O365Author Commented:
The only NDR is the standard Delivery Delay every 4 hours. From On Prem trace, message just sits in the queue . The mail trace at EO shows nothing being received. The TargetAddress at On Prem shows . I have rerun HCW a few times. Same results.
Vasil Michev (MVP)Commented:
Can you check the SMTP logs to get the exact error details? The issue is definitely with your on-prem servers, we just need to find out exactly what is causing it.

Here's a similar issue on the community forums:

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Anthony K O365Author Commented:
You are correct! The issue was with our On Prem network. The smtp protocol logs shows 4.2.2. error message...Delayed. The issue was that our firewall was not allowing SMTP Traffic to any of Microsoft's Online IP's. A Telnet test revealed this.  For migrated users to receive email I place this MX record  ""  as a smart host in my Send connector and had our Network team allow Microsoft's Online IP's in the firewall. See link below. Migrated users are now receiving External emails.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Office 365

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.