there's a distinction that should be made between sending spam and having many contacts. Limiting the amount recipients to a message will prevent spam. Having many contacts doesn't mean the person is a spammer.
A quick google says Google Apps started around feb 2006. Let's assume the user was an early adopter, and today is mar 2011. 10000 contacts / (365 * 5 years) ~= 5 to 6 new contacts a day. Seems possible; maybe in a weekend the user will have 20 new contacts and quiet the entire week... the # of contacts collected throughout the lifetime of an inbox doesn't say anything about the need to send message to all of the contacts.
A quick google says Google Apps started around feb 2006. Let's assume the user was an early adopter, and today is mar 2011. 10000 contacts / (365 * 5 years) ~= 5 to 6 new contacts a day. Seems possible; maybe in a weekend the user will have 20 new contacts and quiet the entire week... the # of contacts collected throughout the lifetime of an inbox doesn't say anything about the need to send message to all of the contacts.