Thanks, Chong, good article. It doesn't mention attachments specifically but I'd assume they 'reside' with the single instance message itself...? -----Original Message----- From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx]On Behalf Of ChongJa@xxxxxxxxxxxxxxxx Sent: Tuesday, August 08, 2006 12:30 PM To: exchangelist@xxxxxxxxxxxxx Subject: [ExchangeList] Re: Attachment Dupes Exchange uses single instance storage based on stores. http://support.microsoft.com/?id=175481 _____ From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Ralph Haney Sent: Tuesday, August 08, 2006 3:23 PM To: exchangelist@xxxxxxxxxxxxx Subject: [ExchangeList] Re: Attachment Dupes Question from non-Exchange expert: If user A sends a 2 MB attachment to all 100 people in the org (via address list) does the Exchange store grow by 200 MB -- or does the store contain one instance of the file and the additional mailboxes 'point' to the referenced attachment? Or, is the environment something entirely different? TIA ~ Ralph