Viktor Dukhovni:
> > On Jul 30, 2019, at 8:52 AM, Rob Maidment <rob.maidm...@clearswift.com>
> > wrote:
> >
> > I already have a before-queue content filter (proxy) that I must use:
> > http://www.postfix.org/SMTPD_PROXY_README.html
> > I would like to make use of a milter as well:
> > http://www.postfix.org/MILTER_README.html
> > I'd like to know if combining both could cause problems. What does the
> > content filter see, for example, if the milter indicates the message should
> > be rejected at the RCPT TO stage?
>
> When the message envelope is rejected, the proxy filter never runs.
>
> I would not recommend mixing milters and proxy filters. The milter
> can never see the message body because, when using a proxy, smtpd(8)
> has no cleanup(8) to which it can pass the milter connection for body
> inspection. The milter will only see the message envelope, and it is
> not clear that the milter will behave correctly at "DOT" when it never
> saw the message body. I could be mistaken. Wietse would know better.
>
> I've not yet used the Postfix milter interface in practice.
As Viktor says, the Milter will not see any header/body/end-of-body
protocol events, and therefore it will reject any attempt to modify
the message or envelope.
Wietse
