Office 365 Migrated mailboxes not receiving External mail

Posted on 2014-09-18
Last Modified: 2014-09-19
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?
Question by:K Anthony O365
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LVL 41

Expert Comment

by:Vasil Michev (MVP)
ID: 40330812
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.

Author Comment

by:K Anthony O365
ID: 40331223
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?
LVL 41

Expert Comment

by:Vasil Michev (MVP)
ID: 40331330
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.
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Author Comment

by:K Anthony O365
ID: 40331483
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.
LVL 41

Accepted Solution

Vasil Michev (MVP) earned 500 total points
ID: 40332030
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:

Author Closing Comment

by:K Anthony O365
ID: 40333511
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.

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