SMTP connections to my server are really slow...What's wrong?

Slow SMTP connections on qmail servers are usually caused by DNS reverse lookup or IDENT lookup issues. qmail is supposed to be run on "well connected" hosts, and consequently is not very good on servers that have DNS issues. If you're starting qmail-smtpd with tcpserver, remove the "-h", "-p", and "-r" options and add "-H", "-P", "-R", and "-l hostname". This should speed things up.

To help with DNS speed it is a good idea to install a local DNS cache such as djbdns (written by DJB the writer of qmail).

Slow DNS requests can also be caused by hugh loads on your server or eaching the "concurrency" of your server. You may need to upgrade your hardware or increase the "concurrency" of your server.