Subj : Re: sap/smtp interaction - wcsmtp build 451.7 To : All From : HECTOR SANTOS Date : Thu Jan 31 2019 19:18:36 Date: Sun, 30 Apr 2006 16:16:36 -0400 From: HECTOR SANTOS To: DAVE GOURD Subject: Re: sap/smtp interaction - wcsmtp build 451.7 Newsgroups: win.server.smtp.&.avs Message-ID: <1146428375.46.1146322326@winserver.com> References: <1146322326.46.0@winserver.com> X-WcMsg-Attr: Rcvd X-Mailer: Wildcat! Interactive Net Server v7.0.454.5 Lines: 53 wrote in message news:1146322326.46.0@winserver.com... > When wcsap rejects a msg, does smtp/WINS close the connection > with the client, or can/is the cip/cdn/hdn allowed to > continue to send data to smtp in the same > connection/transaction session? Should that session end at the > time it is rejected? In general it is bad practice for the server to "DROP" the connection because the client may not understand and will try again. SMTP has five basic commands: EHLO or HELO sender machine name (CDN) MAIL FROM: sender address (FROM) RCPT TO: receiver address (TO) DATA: - email is transferred - QUIT or RSET QUIT For each command, a server response is provided: 250 --> Command ok, continue with next command 50x --> Don't understand the command 45x --> Sorry, don't continue, but you can try again later 55x --> Sorry, don't continue and no need to try again. The only way the client can continue from command to command is with a 250 server response each time. WCSMTP will not drop the connection once a 45x or 55x is sent. It would bad practice. You are suppose to allow the client to issue the QUIT command and then the socket is closed. WCSAP is called at RCPT TO and returns a response to RCPT TO: state to validate all the data up to the point. IP connection address, CDN, FROM and TO. There is 5 minute timer to wait to the client to send the next command. No response, then a DROP is done. The client can send a RSET command which allows him to restart the commands again starting with MAIL FROM:. What you see many times, especially with bulk spammers is that they ignore all server responses and just continue like it was normal. That is why you see 50x errors because the client is out of sync. He is continueing with the next command but he hasn't satisfied the previous command. Hope this helps --- Platinum Xpress/Win/WINServer v3.1 * Origin: Prison Board BBS Mesquite Tx //telnet.RDFIG.NET www. (1:124/5013) .