SenderIPAddress '{0}' contains a third party vendor address and is not allowed for inbound connector of type OnPremises. ...

SenderIPAddress '{0}' contains a third party vendor address and is not allowed for inbound connector of type OnPremises. If you want to restrict mail flow to your organization from third party vendors, please consider creating inbound connector of type Partner. If this address/range belongs exclusively to your organization and you want to configure mail flow originating from On-Premise using it, please contact Microsoft support.