this and several other features are tools i use with tremendous success at battling spam. every MTA connection that violates protocol by making an assumption or posts invalid data for the SMTP phase, gets kicked off with a 421.
-david
On 11/16/2011 09:11 AM, Marc Haber wrote:
I have always interpreted the standard in the way that a client MUST NOT assume that the server supports pipelining before it has advertised PIPELINING. Since PIPELINING is only advertised after the client has identified itself as being ESMTP compliant by saying EHLO instead of HELO, I believe that the client MUST wait with his EHLO until the server has shown its banner. Forcing synchronization is a very effective means of spam protection since most spam bots just blast away with EHLO, MAIL FROM without bothering to wait for the server's banner. Greetings Marc