Hi All I have 400 users. For the past 5 years with Ex 2003 each user was assigned a 300Mb inbox through system policies. Most users hit 150-200Mb before some form of archiving pulled old mail out. Worked really well. About six months ago I upgraded from Ex 2003 to 2010. After moving to new hardware with larger drives, most users immediately hit the 300Mb cap. I raised the cap to 600Mb and now many of my users are hitting that. This is significant - to go from 5 years of avg 175Mb mailbox sizes to needing up to 600Mbs per user over a six month period?? I understand that SIS is gone, but come on! I even have a third party archive solution that I've had to increase drive capacity on to more aggressively pull mail out. You might suspect increased mail traffic but nothing has changed - we've long used Postini spam filtering and continue to do so, we've even reduced the size of our workforce in the past year. Somebody tell me I'm missing something or I've got the "use excessive capacity" switch flipped. Mark

Hello If you are Planning to reduce the Mailbox sizing you need to plan for limitations for database usage and by default exchange 2010 is having 2 GB. You can restrict the total size of a message or the size of the individual components of a message, such as the message header, the message attachments, and the number of recipients. Restrict Incoming and Outgoing Size Difference Between Exchange 2003 and 2010 Message Size Limits is Exchange 2003 treats each member of an expanded distribution list as one recipient. Exchange 2010 treats a distribution group as one recipient Pleaes go through this links and check more about it. http://technet.microsoft.com/en-us/library/bb124345.aspx http://technet.microsoft.com/en-us/library/aa998353.aspx Thanks Mhussain

Hello If you are Planning to reduce the Mailbox sizing you need to plan for limitations for database usage and by default exchange 2010 is having 2 GB. You can restrict the total size of a message or the size of the individual components of a message, such as the message header, the message attachments, and the number of recipients. Restrict Incoming and Outgoing Size Difference Between Exchange 2003 and 2010 Message Size Limits is Exchange 2003 treats each member of an expanded distribution list as one recipient. Exchange 2010 treats a distribution group as one recipient Pleaes go through this links and check more about it. http://technet.microsoft.com/en-us/library/bb124345.aspx http://technet.microsoft.com/en-us/library/aa998353.aspx Thanks Mhussain

Run Get-MailboxFolderStatistics http://technet.microsoft.com/en-us/library/aa996762.aspx on some sample mailboxes and see where the growth. I agree with you however. In my experience, 2010 stores are larger than previous versions and I dont think its just SIS. I also suspect the Dumpster 2.0 logic plays a part.

I think the most important reason is that Single Instance Storage is removed in Exchange Server 2010. The size of mailbox database should be much larger than Exchange 2003. http://exchangeserverpro.com/what-is-the-real-effect-of-removing-single-instance-storage-in-exchange-server-2010 Also, as above mentioned, please assure the Message size limits are configured in Exchange 2010. To check the detail mailbox’s size in EMC, I suggest you refer to the following article: http://exchangeshare.wordpress.com/2008/04/23/emc-where-are-mailbox-total-items-size-kb-columns/ Thanks. Novak Wu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com

How is thing going on? If there is any progress or question, please feel free to post it here. Thanks. Novak Wu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com

Another factor with Exchange 2010 is 'Larger and Sequential I/O', which gives more holes inside the database file. http://technet.microsoft.com/en-us/library/bb125040.aspx lasse at humandata dot se, http://anewmessagehasarrived.blogspot.com

It's because they removed single instance storage from Exchange, which I think is a pretty dumb move...