Number of copies of messages?

[Bob Jones]

Hello all.  I've been tasked with looking at changing our mail 
services and one of the options is Cyrus.  One question that will 
greatly impact the decision is this:

How many copies of a message are saved in the message store?  I know 
Cyrus has a db backend, so we're wondering if one message is sent to 
all users on the server, is only one copy of that message saved in the 
store or is there an individual copy of each message for each user saved?

Many thanks,
Bob Jones
OIIT
Board of Regents, USG