MX record in diffrent domains points to the same mail server

[jsayra at ssa.siemens.es]

This is the scenario:

- Three domains: domainA.com, domainB.com and domainC.com. and I am
authority all of them.
- The three domains are servered by the same name server.
- One mail server in domainA.com as mailsvr.domainA.com

I want all the MX records in the three domains point to the mail server in
domainA.com. Something like that:

- db.domainA file:  "domainA.com.  MX  10  mailsvr.domainA.com."
- db.domainB file:  "domainB.com.  MX  10  mailsvr.domainA.com."
- db.domainC file:  "domainC.com.  MX  10  mailsvr.domainA.com."

Is this possible such solution?
Have I to put a glue record in the db.domainB and db.domainC files for the
mailsvr.domainA.com record?

Regards,
JSAyra