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:


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 [email protected] it has to be [email protected]! 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: