Can't Turn On Exchange Online OnPremises Inbound Connectors

Copper Contributor

Seems that Microsoft have made some changes without any notification that you can now no longer setup OnPremises Inbound Mail Connectors in Office 365 without having to contact Microsoft Support to get these enabled. Seems to only apply to any new tenants setup from about February 2023, previous tenants don't have this issue.


Problem is, I have been trying to get support to enable this for a new client we just moved to Office 365 as the require this for their Accounting/LOB software they run but it has nearly been a week and still can't get support to sort it.


Despite them providing me with the link I included above stating that these connectors will now be disabled by default and we have to contact support with a business justification for it to be enabled they are giving me a huge run around making me send through screen recordings of me trying to set it up both from the website as well as PowerShell. They now want me to run a network diagnostic tool on the machine I am doing this from (have tried doing this on both my desktop PC as well as my laptop from multiple different internet connections) and send it through so they can analyse.


Anyone else come across this and if so were they able to get it resolved? Or is there anyone from Microsoft reviewing these posts that can help??

5 Replies
Same issue. I manage a few different 365 tenants and this particular was was created around January '23. I now have 3 connectors (email security and signature platform) that I can't turn on and have been asked by MS to justify the connectors. To say it's made my blood boil is an understatement. Only MS can pull something like this and we just have to obey.

@xtremetoonz Have a look here, I also posted on the Partner Support page and have slightly more response but still battling with Microsoft Support to get it resolved after about 3 weeks now. Luckily I was able to setup an SMTP relay to use in the meantime otherwise the customer would be fuming!


Yes, seems mot much release related to this, for your case, may I know the version of your on-prem Exchange server?


Configure mail flow using connectors in Exchange Online | Microsoft Learn

We aren't using an on-prem Exchange Server, the client has a software package that they email their clients directly from so we need to allow relaying from their IP address via Exchange Online to send these email out.

Normally we setup a an Inbound Mail Connector selecting from "Your organization's email server" to Office 365 and configure with the IP address but seems Microsoft have disabled this functionality and you have to provide business justification for them to enable, just seems no one on their support team knows how to do this as I have been going round in circles!

Stupid thing is Microsoft still list this as an option for setting up multifunction devices or applications to send emails:



The resolution is to use the new "Partner Organization" to connect to a 3rd party. I just got off a Teams call with MS support showing me this. Maddening there's no documentation on this yet.