Hello,
Have you ever seen this error in your qmail-send logs?
CNAME_lookup_failed_temporarily._(#4.4.3)
This can mean that someone you are trying to send e-mail to has violated the DNS protocol and is sending oversize DNS responses to your server.
There are three solutions that can help with this problem.
- Install a djbdns DNS Resolver on your qmail server.
- Install the Big DNS patch for qmail.
- Ask the entity responding with oversize DNS results to fix their DNS.
-Raymond