答え1
サフィックス自体できない。
http://www.postfix.org/BUILTIN_FILTER_README.html
Header/body checks cannot depend on the recipient of a message.
One message can have multiple recipients, and all recipients of a
message receive the same treatment. Workarounds have been proposed that
involve selectively deferring some recipients of multi-recipient mail,
but that results in poor SMTP performance and does not work for non-
SMTP mail.
Some sources of mail send the headers and content ahead of the
recipient information. It would be inefficient to buffer up an entire
message before deciding if it needs to be filtered, and it would be
clumsy to filter mail and to buffer up all the actions until it is
known whether those actions need to be executed.
ミルトが必要です。