Today I spent a good amount of time checking out the Linux server used by our company. We have just configured the server to host about 30 different e-mail accounts and found that some users are having trouble receiving and sending mail.
After perusing the logs for a while, I noticed that users weren’t using the correct username when logging in. This explained why they weren’t able to receive mail. As far as sending, I saw a mysterious error in the logs that read “CNAME_lookup_failed_temporarily.”.
This turns out to be a deficiency in QMail which attempts to do a DNS lookup on the recipient address to make sure that the address being sent to is valid. Only problem is, it queries the entire DNS record, not just the CNAME record to workaround a bug in CNAME lookups. I found that installing “dnscache” should fix this problem so I installed it and hope this will do the trick. I see you have all fallen asleep after reading this mindless drivel… sorry about that.