Mails from external cannot be received after migration to Exchange Online

After migrating several users from Exchange 2010 to Exchange Online it can happen that some of the users are not able to receive e-mails from external senders.

In a normal case, you would go and check the send/receive connector settings.

You can find more info about this in the following article:

https://technet.microsoft.com/en-us/library/ms.exch.eac.connectorselection(v=exchg.150).aspx

 

But this is not the solution in our case. The problem is, that not all of the users have this issue.

So let’s have a look on how we found out more about this issue and how to fix it:

 

After sending an e-mail to an user with having this problem, I received the following error Message:

If we have a closer look at this error message, we can see that there are too many hops in the request:

In our case we are running a hybrid Exchange environment. All e-mails are sent and received by a smart host.

This information tells me that something could be wrong with the routing address, so let’s have a look at it:

as we can see, the wrong entry is set as routing mail address. Instead of the address alias@contoso.com it has to be alias@tenant.mail.onmicrosoft.com! So we corrected it.

with this information the on premise Exchange server is able to communicate with Exchange online, again.

 

You can find more information about ROUTING MAIL ADDRESS here:

https://technet.microsoft.com/en-us/library/jj937232%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

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  1. Pingback: Merge Exchange online Mailbox with on-premise AD account - MSB365 - The Microsoft Blog

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