I'm wanting to run this by everyone here to make sure this makes sense.
We have a customer that needs to bypass their internal DNS when sending email to our domain. We want their exchange server to send directly to our spam filter which then get's dropped into our exchange server.
They are a completely separate company, and we do not share any domain or have any federated services with them.
Would this be as easy as having them create a new send connector on their exchange server to send email for our domain to a smarthost and that smarthost would be our spam filter which is a barracuda filter. Or is there more to it than that?