multiple domains and mx records

[Jared]

Our company has two domains (domain1 & domain2).  Each domain has a mail
server called mail.domain1.com, and mail.domain2.com.  I have one
nameserver/firewall/gateway serving both domains, gw.domain1.com.  This is
my named.conf


zone "domain1.com" {
        type master;
        file "s/domain1.com";
};

zone "domain2.com" {
        type master;
        file "s/domain2.com";
};

The record file for domain1 looks like

@               IN      SOA gw.domain1.com. root.domain1.com. (
                                14      ; Serial
                                10800   ; Refresh
                                3600    ; Retry
                                3600000 ; Expire
                                86400   ; Minimum
                        )
                IN      NS                  gw.domain1.com.
                IN      MX      100     mail
gw            IN      A                   1.2.3.4
mail          IN      A                   1.2.3.5

The record file for domain2 looks like

@               IN      SOA gw.domain1.com. root.domain2.com. (
                                10      ; Serial
                                10800   ; Refresh
                                3600    ; Retry
                                3600000 ; Expire
                                86400   ; Minimum
                        )
                  IN      NS              gw.domain1.com.   #(is this the
problem?)

                  IN      MX   100     mail
mail            IN      A                1.2.3.6


The problem is when you ping mail.domain2.com, the address for
mail.domain1.com comes up.  How can I have both machines named mail for
their respective domain?

Thanks
Jared
jared at software2010.com