Some clients might experience a very slow SMTP connection on a Plesk 7.1.7 server running qmail. The main reason for the delay is cuased by a Reverse DNS lookup performed on each IP address connection to the SMTP server on port 25. If your server does not have good DNS connectivity or the owner of the IP address’s DNS servers are overloaded, you may notice a delay of up to 60 seconds (the default) to be able to send mail.
I suggest that you update your
server_args key in both files, as suggested below:
server_args = -Rt0 /usr/sbin/rblsmtpd -r sbl-xbl.spamhaus.org -r bl.spamcop.net ......
You may want to replace
bl.spamcop.net with your favourite RBL list. You may also add additional RBL entries by specifying additional