COS Settings for IMAP Clients

[soxfan]

Just re-reading the Zimbra OS Admin Guide as I prepare for an upcoming migration to Zimbra, and something caught my attention. In Chapter 7, Managing User Accounts section, Class of Service sub-section there is a note that says "COS settings assigned to an account are not enforced for IMAP clients.". This note has me somewhat confused. I can see where some of the COS settings would only be applicable to the Web client, but others like password restrictions, account quotas, message lifetimes to me would seem to be things that are controlled at the server level. How can these settings be affected by what type of client is used? What am I missing here? Could someone please clarify?

TIA,
John