I was following this guide to set up a catchall account. One of the steps instructs you to set all domains as "internal relay". When I do that, I get the following warning:
There is no outbound connector to deliver mail for this domain. Make sure that there's an Outbound Connector of the type OnPremises that matches every 'internal relay' accepted domain. The connector can either have the AllAcceptedDomains flag enabled or have a recipient domain that matches the accepted domain.
The guide does not mention this at all. If I continue following the guide, will my email still function? If not, how do I add an outbound connector?