smtp server and CNAMEs

[Harry Putnam]

Novice Alert!
Setup: Gentoo linux (kernel 2.6.15-r3)
       bind-9.3.2
       sendmail-8.13.4
Using bind/named as simple authoritative home lan server

I want to start using a home machine running bind as my mailhub as
well for home lan.  It won't be subjected to the rigors of the big
wild internet but I'd like to have it setup as if it would for the
experience. 

I've setup up a CNAME in zone.192.168.0 that looks
like this:

    $TTL 1D
  local.net0.     IN SOA    reader.local.net0.  hostmaster (
                          200405191 ; serial
                          8H        ; refresh
                          4H        ; retry
                          4W        ; expire
                          1D )      ; minimum
  local.net0.     IN     NS      reader.local.net0.
  smtp.local.net0.         CNAME		reader.local.net0.
  
  ; just in case someone asks for localhost.local.net0
  localhost.local.net0.        A       127.0.0.1
  [...]

How is that reflected in this zones reverse pointers file?  Or is it
all just handled by the CNAME line? Currently the revers file looks like:

  $TTL 1D
  0.168.192.in-addr.arpa.  IN SOA  reader.local.net0. reader.reader.local.net0. (
                200405190  ; serial
                28800      ; refresh (8 hours)
                14400      ; retry (4 hours)
                2419200    ; expire (4 weeks)
                86400      ; minimum (1 day)
                )
  ; define the authoritative name server
  4.0.168.192.in-addr.arpa.  IN NS reader.local.net0. reader.reader.local.net0.
  ; our hosts, in numeric order
  1.3.0.168.192.  IN PTR  mob2.local.net0.
  2.4.0.168.192.  IN PTR  reader.local.net0.
[...]