>Как именно средствами Sendmail запретить прием внешних писем от своего домена
Ну примерно так:
Slocal_check_mail
R$+ $1 $| $&{client_name}
R$+ $| $=w $@ $1 # local connection
R$+ $| # local mail
R $* $| $* $: $1 $| $>CheckLocalNet $2
R $* $| $* $: $1 $| $2 $>CheckLocalUser $1
R $* $| $* $* $: $1 $| $3 $2
R $* $| CONN_REMOTE USER_REMOTE $@ $1
R $* $| CONN_LOCAL USER_REMOTE $@ $1
R $* $| CONN_LOCAL USER_LOCAL $@ $1
R $* $| CONN_REMOTE USER_LOCAL $#error $@ 5.7.1 $: "571 foreign host " $&{client_name} " can not send mail from local user " $>decanonify $1
R $* $#error $@ 4.5.1 $: "451 unknown internal error"
SCheckLocalNet
R $=w $@ CONN_LOCAL
R $=R $@ CONN_LOCAL
R $+. $=R $@ CONN_LOCAL
R $* $@ CONN_REMOTE
SCheckLocalUser
R $* $: $>canonify $1
R $* < @ $=w . > $@ USER_LOCAL
R $* < @ $=R . > $@ USER_LOCAL
R $* < @ $+ . $=w . > $@ USER_LOCAL
R $* < @ $+ . $=R . > $@ USER_LOCAL
R $* < @ $+ . > $@ USER_REMOTE
R $* $@ USER_LOCAL