Questioning myself

[Patrick B. Jones]

I apologize for how basic this question is going to be. I am in a state of
self distrust.......
I am running BIND-9.1.1. Question is this:

I want to have email for domain1.com and email for domain2.com have their mx
records point to the mx of domain3.com.
This is what I have in my .db

Zone domain1.com.db

; Mail
	MX	domain3.com
~~~~~~~~~~~~~~~~~~~~~~~~
Zone domain2.com.db

; Mail
	MX	domain3.com
~~~~~~~~~~~~~~~~~~~~~~~~
Zone domain3.com.db

; Mail
	MX	mail
; IP
domain3.com		A	192.168.1.5
mail			A	192.168.1.5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Is this ok? These are not subdomains, rather they are 3 different domains.

~TIA

Patrick Jones