I'm testing zimbra right now and thinking in migrating from my current solution based in postfix+ldap+courier imap+clamav+amavis+spam assasin+squirrelmail to zimbra. I work in a college and we have 10.000 accounts with a goal of incrementing that number to 40.000 in the next 3 years. Currently, only one MTA is enough for our mail load. We have 2 servers with squirrelmail and 3 servers with ldap.
One of my doubts is: can only one zimbra mailbox would be sufficient for our 10K users? I would like to know about your experiences with zimbra: how many accounts is reasonable to attend with one server, and, if you manage hundreds of users, which configuration you've found the best for your needs.
Thanks in advance.