Postfix v.3.0.0 MILTER_README says:
Sendmail macro emulation
Postfix emulates a limited number of Sendmail macros, as shown in the
table.
Some macro values depend on whether a recipient is rejected (rejected
recipients are available on request by the Milter application).
Different
macros are available at different Milter protocol stages (EOH =
end-of-header,
EOM = end-of-message); their availability is not always the same as
in
Sendmail. See the workarounds section below for solutions.
|Sendmail macro |Milter protocol stage |Description
|
| | |
|
|i |DATA, EOH, EOM |Queue ID, also
Postfix |
| | |queue file name
|
| | |
|
And in the "Workarounds" section
The problem is that Milter applications expect that the queue ID is
known
before the MTA accepts the MAIL FROM (sender) command. Postfix does
not
choose a queue ID, which is used as the queue file name, until after
it
accepts the first valid RCPT TO (recipient) command.
However:
# postconf -d milter_rcpt_macros
milter_rcpt_macros = i {rcpt_addr} {rcpt_host} {rcpt_mailer}
Also, the setting "smtpd_delay_open_until_valid_rcpt = no" assures that
the queue ID is known at RCPT time, making it possible for Postfix to
provide it to milters as the default setting says it will.
( Complicating matters, the only milter I use, MIMEDefang, seems to have
internalized the principle that Postfix will never tell it an ID at RCPT
time. Hurrah for implementation-agnostic standard APIs... )
