Email/Calendar/LDAP

[Troy Knabe]

I am a school district with approximately 16000 students and 3500 staff 
members.  I am currently using Sun's JES suite for ldap/email/calendar. 
  Every other box I manage is Red Hat, and I am interested in what 
other's are using for this.

Cost is the biggest issue, but we do need some level of support.

We use ldap for many other internal application authentication and 
authorization.

We are migrating towards Kerberos for authentication and still wanting 
to use ldap for authorization, but JES mail/calendar doesn't support 
Kerberos.  So a solution that does would be nice.

Currently all is run on a single T2000, which handles the load easily, 
but I would like to move towards a separate box for each service and be 
able to scale it easily for performance and redundancy.

TLS/SSL is a must for not just authentication but all internal email 
traffic.  I realize kerberos will handle this for us if we can get email 
to it.

I use a separate box at our gateway for spam/virus filtering.

Thanks
-Troy