Martijn de Munnik: > Hi List, > > Some of our customers use our mailservers as antispam/antivirus gateway. > So our server accepts mail, does some spam and virus checking and > delivers the mail to a remote server. Of course I don't want to accept > mail for non existing users so our mailserver verifies the recipient. So > far so good. > But when a spam run is started and our server receive over 100 messages > per minute the final server wouldn't handle the verifies anymore and is > responding: > > [ID 197553 mail.info] NOQUEUE: reject: RCPT from > smtp.zonder.com[64.244.96.100]: 450 4.1.1 <rerer...@example.com>: > Recipient address rejected: unverified address: host > xxx.xxx.xxx.xxx[xxx.xxx.xxx.xxx] refused to talk to me: 421 too many > connections; from=<> to=<rerer...@example.com> proto=ESMTP
To make fewer connections to the downstream machine, see: http://www.postfix.org/master.5.html http://www.postfix.org/postconf.5.html#transport_destination_concurrency_limit Wietse
