Exchange Server Size

Pete,

This really depends on how much space you are going to allocate to users. I usually figure about 50 megs per user and I enforce mailbox limits (they get the nag email saying they have exceeded their limit).

I wouldn't go less than a dual processor unit, with a minimum of 256 memory. Raid 5 arrays will definately be in order for business continuity purposes.

Let me know if you have any other questions.

bryanb is correct. A couple of other points to consider:
Are there going to be Public folders? If so, count those as users for use of sizing. You can apply different size limits to these as well.

Are any of your users remote? Will they need additional services (POP3, IMAP, LDAP, Outlook Web Access). If some of these are used, you may need either an additional server or IIS installed on the NT server, increasing your disk and memory requirements.

While discussing disk (RAID), also make sure you have an "Exchange aware" backup application.

Agree with Proposed Answer 1 and 2. If you are so concerned with the size, why don't you configure your exchange servers as POP3, in this way, emails will be downloaded to users thus freeing diskspace from server, however, the disadvantage is you will not be able to back up email messages then.