What happens if I point an MX record to the wrong mailserver?

[Myron Johnson]

I was wondering what happens if I do the following? 
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1) Create a new domain, "junk.com". 

2) Point the DNS MX record for Junk.com to my mailserver at
E-Rice.Net.
BUT...The domain name at E-Rice.Net is "mydomain.com". 

3) Create a mailbox on my mailserver named "test" (test at mydomain.com) 

4) Send mail to test at junk.com 
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Will the mail be received into the "test" mailbox at "mydomain.com",
or will it be rejected?

Thanks!