I ran into the same issue.
I believe it stems from the fact that all mail going through the box starts at the same point, and "inbound" vs. "outbound" is really only to provide different policies. Inbound and outbound routing is all to do with the domain routes.
What I did was go to Mail Policies and added a new policy.
I chose Outbound mail flow, and under rules, set the source IP address to the internal mail server. This basically tells the server to consider any mail it receives from my Exchange server as "Outbound". Anything else is "Inbound".
I had done this. Initially I had set the new policy as "outbound" and did not specify and IP address match. I thought that the policy would apply to "oubound" mail. What I found was that all mali was being processed by the this policy. So I added the IP addres match rule so that only mai lfrom internal filters would be processed by this policy. All other mail fell through to the default (inbound) policy. So for most things, like spam filtering. encryption rules etc- this works great.
However, there does not seem to be an option in the policy for specifying the SMTP masquerading options.
I could have my masquerading set up as
alias1 -> username1
to make sure that they only apply to true incoming mail.
But then what is the purpose of defining oubound smtp masquerading if I can't use them?
I had set email policies. I see there are also protocol policies and rules. Maybe that is where I need to fix it.
Openned a ticket with McAfee support. it looks like I would need to be in transparent bridge mode for the system to distinguish between incoming and outgoing mail.