>>         I'd like to swap this into below:
>>                 sendmail.cf: listens to both IPv4 and IPv6 socket
>>                 sendmail-IPv4only.cf: listens to IPv4 socket only

> Leave it alone.  The default is fine.

So, the default setup for every native NetBSD service except sendmail
will be to listen on the IPv4 and IPv6 socket, and sendmail will be
different?  That doesn't seem fine to me.