I think both the sendmail rc.d scripts are broken. They should not use
/usr/sbin/ and should not use /etc/mail/, It is a convenience for some,
but it is not the pkgsrc way. As an example, see alternative exim's
rc.d script:
command="@PREFIX@/sbin/${name}"
required_files="@PKG_SYSCONFDIR@/configure"
Or pkgsrc postfix's rc.d script:
postfix_command="@PREFIX@/sbin/${name}"
: ${required_files=`@PREFIX@/sbin/postconf -h config_directory`/main.cf}
(Also note that on various pkgsrc systems, /usr/sbin/sendmail is not the
mailwrapper. But may be some sendmail that the pkgsrc user doesn't want
to use -- that is why they installed from pkgsrc.)