2 Server Dell c1100 2 x 12 Intel(R) Xeon(R) CPU L5639 @ 2.13GHz
OS: Linux 3.2.29 x86_64 Slackware 14.0
Users ~ 41199
Maildir size: ranging from few Kbs to about 8 Gbs
Dovecot version: 2.0.21
Webmail Client Software: Roundcube and other made by mesi.com.ar team.
Filesystem ext3 with 32k folders fix using 7 depth levels /var/spool/mail/012345/0/1/2/3/4/5/6