This should resolve all host references to the same mail exchange.
Is that what you are asking?
Code:
example.com. IN MX 10 mail.example.com.
mail IN A 192.168.0.3
Host1 IN CNAME mail
Host2 IN CNAME mail
Host3 IN CNAME mail
Host4 IN CNAME mail
Host5 IN CNAME mail
Host6 IN CNAME mail
Host7 IN CNAME mail
Host8 IN CNAME mail
Host9 IN CNAME mail
Host10 IN CNAME mail