Well, I spent the better part of my day researching email issues on my server. Here are the problems I was having and what I did to fix them. I hope this may help someone:
Server is an AMD White Box Linux with Plesk
1. Undeliverable email/cname errors from QMail:
It seems the DNS servers I had listed in my /etc/resolv.conf file were causing me problems. Here is my edited /etc/resolv.conf file with new RackShack servers:
search localdomain
nameserver 207.218.192.38
nameserver 207.218.192.39
2. Stalls of 30-40 seconds when connecting to SMTP mail before mail would be sent:
Recently, my cable ISP moved to a new network. After the change, I began getting these stalls when trying to send mail. It seems the problem is with my provider improperly handling QMail's reverse dns lookup requests.
You can disable QMail's reverse dns lookup by adding a -R argument to /etc/xinetd.d/smtp_psa. Here is my edited /etc/xinetd.d/smtp_psa file:
service smtp
{
disable = no
socket_type = stream
protocol = tcp
wait = no
user = root
instances = UNLIMITED
server = /usr/local/psa/qmail/bin/tcp-env
server_args = -R /usr/local/psa/qmail/bin/relaylock /usr/local/psa/q
mail/bin/qmail-smtpd /usr/local/psa/qmail/bin/smtp_auth /usr/local/psa/qmail/bin
/true /usr/local/psa/qmail/bin/cmd5checkpw /usr/local/psa/qmail/bin/true
}
Notice the -R switch. This should be all you have to add to your smtp_psa file to disable QMail's reverse dns lookup.
*NOTE* I'm not exactly sure of the security/spam implications of disabling reverse dns. Use caution here!
Hope this helps
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