@nas, I think myorigin is good at default value in our setup, where local mail is not used
Who prevents you to add this parameter and make some tests 
I’ll make a test as soon I have some spare time in the week.
Should someone have a configuration suggestion please post it. That will speed up the test.
BR,
You’re absolutely right!
Nobody, but something:
- I’m continuing think as with Windows OS and I’m afraid do not broke something;
- Lack in my Linux knowledge.
But again, everything is about me.
BR,
Gabriel
Don’t worry friend, we’re all here to learn something new, every day 
Very sorry but my time has been very limited to test a multi-domain setup. When i saw that it wasn’t as simple as just adding a config setting i removed my second and third mail domain to prevent the problem from happen which solved my problem temporary.
BR,