Wietse Venema:
> Nikolaos Milas:
> > Hello,
> >
> > We are running 2.9.4 on CentOS 6.5 as a mail gateway.
> >
> > A mail admin of a cooperating entity has reported that their sender
> > checking to our org produces a protocol error and after that their
> > system marks our mail as junk.
> >
> > Here is a session they provided (I only changed the mail adress username
> > with "existing_user"):
> >
> > 220-mailgw1.noa.gr ESMTP NOA Mail Srv XAPITI XPICTOY
> > HELO lala
This buggy client sends SMTP commands before Postfix has sent the
complete "220" SMTP greeting.
You can whitelist this buggy client with postscreen.
Wietse
