I've posted this to the Wiki as requested.
Servers: 2 SuperMicro single-Xeon (dual-capable) 2.8, 1gb RAM,
mirrored SATA boot
Storage: 1 SuperMicro dual-Zeon 2.8, 2gb RAM, 600GB RAID5 SATA shared
via NFS over GigE
OS: RHEL 4
Users: 10,000 mostly POP users, SquirrelMail IMAP
Auth: MySQL
Maildir size: daily averages about 50gb
Dovecot version: 1.0 beta 5
Client Software: squirrelmail, outlook, outlook express, thunderbird,
eudora, Apple Mail, Claris Emailer, and other odd clients too
numerous to mention
This system is intentionally over-engineered, to replace the single
server Courier-IMAP system that it replaced. Load on each Dovecot/
SquirrelMail server is very low and allows for a lot of growth.
Our incoming MTA is Exim, on another pair of SuperMicro machines
writing to the same NFS over GigE.
-- Roger J. Weeks Systems & Network Administrator Mendocino Community Network