Does UW IMAP Match Your Needs?
Many sites select UW for its simplicity. For many system administrators, the ability to just slap an entry into your
imapd.conf file and have a functional IMAP server with literally no time spent on configuration is highly attractive.
If a large proportion of your Unix users access traditional Unix mail directly or with native mail clients, UW will allow you to gradually move the users from traditional Unix mail access methods to IMAP. UW lets you add IMAP to the mix without taking anything away. As we’ll see a few chapters later, the Cyrus IMAP server requires “all or nothing.” The only way to access Cyrus mailboxes is via IMAP—direct access is not possible because the mailboxes are owned by the Cyrus system and are invisible to normal users.
If you have mailstores in two or more formats or you need to have shell account access to your mailstore, UW is probably the best choice. If you have a modest number of users (under 15,000, say) and can suitably work around the lack of ACL and IMAP quota support, then UW IMAP will probably work for your site.
If you need something that scales to many users more easily, then Cyrus is the best choice. Cyrus fits better because of ACL and IMAP quota support. If you have no need for simultaneous shell account and IMAP access to the same mailboxes, then you would probably be better served by Cyrus.
A typical growth path for an email infrastructure goes something like this:
The first email system is usually something ...