Tag Archives: Office 365

Office 365 and Exchange 2007 Mail Flow Issue for Sub Domain

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Office 365 logo

I have recently had an Office 365 and Exchange 2007 Mail Flow Issue for Sub Domain. We have our primary users on user.name@domain.com and have setup Office 365 to process mail for user.name@sub.domain.com .

The setup for Office 365 went extremely smoothly (with a lot of help from a friend – you know who you are J.P.) and I have integrated Office 365 with our on-premise Active Directory using ADFS and Synchronization Service Manager for Single Sign On.

However when a user,  user.name@domain.com tried to send an email to user.name@sub.domain.com using the on-premise Exchange 2007 the mail was not delivered.

User user.name@sub.domain.com could send email to user.name@domain.com without any problems, but again a reply from user.name@domain.com was not delivered.

I investigated further on the Exchange 2007 Server and found that in Queue viewer there was an Unreachable Domain queue with emails which could not be delivered. Continue Reading