Setup a transparent proxy with 3 easy steps

First, Squid server installed (use up2date squid) and configured by adding following directives to file:
# vi /etc/squid/squid.conf

Optimizing Sendmail

Most of them involve changing the daemon’s configuration in /etc/sendmail.mc and rebuilding sendmail.cf
Specific things that can affect performance:
dnl # Sendmail, Chap 24.9.13, Page 955
dnl # Disable re-write of queue control file (will result in duplicates
dnl #   if the daemon is interrupted during a delivery)
define(`confCHECKPOINTINTERVAL’,`0′)dnl