Can you specify a low-priority mx server when sending email?

I have 3 MX servers low, medium and high priority.





most email is sent through the high-priority mx server and rarely (if ever through the low-priority server).





I'd like to TEST the low-priority server to make sure that it delivers mail properly without boosting the server to highest priority.





Any idea how to do this?

Can you specify a low-priority mx server when sending email?
I think it's possible by using the desired SMTP server's host name as the domain portion of the mail address.





Say, mx1.bar.com and mx2.bar.com serve for the foo.com domain. You can send mail to either you@foo.com, you@mx1.bar.com, or you@mx2.bar.com.