DNS or IDENT Lookups Can Make SMTP Slow

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If qmail-smtpd is slow to respond to connections, the problem is probably because of Domain Name System (DNS) reverse lookups or IDENT lookups having to time out. If the problem is DNS-related, the best fix is to correct your DNS configuration. Another approach is to configure tcpserver not to attempt the lookups. That might be an option if you don't need the information these lookups provide. This can be accomplished by removing the -h, -p, and -r options and adding -H, -P, -R, and -l 0 (ell zero).

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