Andrew Beverley:
> On Thu, 2015-10-15 at 21:09 -0400, Wietse Venema wrote:
> > > Clearly the sending server is not talking the SMTP protocol correctly,
> > > but would someone mind explaining the reason why please?
> >
> > This error message is described in a "readme" tutorial.
> > http://www.postfix.org/POSTSCREEN_README.html
>
> Thanks Wietse. Sorry, I went straight to Google, rather than diving into
> your excellent documentation!
>
> I still don't quite understand what's going on though. I've tried the
> test myself with a telnet connection, and I can see that I initially
> receive the teaser banner. When I then reply to that with "HELO ..." and
> try sending an email, I do indeed receive a protocol error.
You did not behave as a legitimate MTA.
The postscreen_greet_banner "220-text..." teaser banner becomes the
first part of a multi-line server greeting.
220-first line from postscreen
[6-second pause]
220 last line from smtpd
The client must wait until it receives the last line.
Wietse
