How many mailserver IP addresses can be associated with a .mail domain?
An unlimited quantity. One will be able to assign name/IP combinations for each of ones servers. For example: mailout-01.example.com.mail A 233.0.42.41 mailout-02.example.com.mail A 233.0.42.42 mailout-03.example.com.mail A 233.0.42.43 remote-factory.example.com.mail A 2.111.244.10 list-server.example.com.mail A 127.0.14.