Date: Tue, 25 Mar 2003 02:30:45 +0100 From: Olivier Dony <oli@studyssimo.be> To: questions@FreeBSD.ORG Subject: (SOLVED) Re: [Urgent] sendmail not echoing back during smtp connection Message-ID: <20030325013045.GA81317@naboo.blacktrap.net> In-Reply-To: <020201c2f22e$feeb0df0$1502a8c0@blacktrap.net> References: <020201c2f22e$feeb0df0$1502a8c0@blacktrap.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Mar 24, 2003 at 06:58:21PM +0100, Olivier Dony wrote: > Help! I have a production server where sendmail suddenly stopped > answering smtp connections! > I have tried killing it and restarting it, but this doesn't change > anything. > The config didnt change, it just started to do this progressively, > from what I can see in the logs with increasing numbers of > "[xxx.xxx.xxx.xxx] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA" > > If I connect to port 25 the connection is established but nothing is echo'd, > like no sendmail greeting, no reply whatsoever to smtp commands. > So all MTAs are timing out connecting to my server! But the delivery still works > fine, ie if I telnet to port 25 and give a valid mail from, rcpt to, data, etc, > without waiting for SMTP answers, the mail is delivered fine in my inbox... Here is the explanation if someone ever gets the same problem: DNSBL's are somehow blocking every connection, so the solution is to remove every DNSBL from sendmail's config and restart it and the problem goes away. (A lot of thanks to the sendmail-questions mailing-list :-) I was using 4 of them : relays.ordb.org, list.dsbl.org, dun.dnsrbl.net and spam.dnsrbl.net. I will try and see which one(s) is(are) causing the problem when the mail traffic calms down a bit. This is probably due to the way DNSBL is implemented that nothing is logged regarding this problem and the client is just left there to timeout, and the timeout is really logged. This is what mislead me, but the progressive increase of the "did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA" messages in the log should be a red flag for anybody using DNSBLs. Hope this can help someone. Thanks for reading ;) Olivier To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030325013045.GA81317>