We are required to create a distribution group of approx. 18,000 members. Other than message size limits are there other best practices available to using a distribution group of this size? Are there any restrictions with exchange 2003 in creating a list this size?

This may answer your question: http://msexchangeteam.com/archive/2009/02/19/450729.aspx Which refers to this article: http://technet.microsoft.com/en-us/library/active-directory-maximum-limits-scalability(WS.10).aspx#BKMK_Users

http://technet.microsoft.com/en-us/library/bb124345(EXCHG.80).aspx "The primary difference in message size limits between Microsoft Exchange Server 2003 and Exchange Server 2007 is in the handling of recipient limits. Exchange 2007 treats a distribution group as one recipient. Exchange 2003 treats each member of the expanded distribution list as one recipient. This change was implemented to avoid the partial message delivery scenarios that may occur in Exchange 2003. Partial message delivery occurs in Exchange 2003 if the number of individual recipients and the recipients that are contained within the distribution list exceeds the specified recipient limit. The total number of message recipients isn't known until after distribution list expansion. Message delivery occurs as the distribution list is expanded until the number of recipients reaches the specified limit. The remaining recipients don't receive the message, but at least the sender receives a non-delivery report (NDR) for each unsuccessful delivery. However, if delivery failure reporting is disabled for the distribution list, the remaining recipients wouldn't receive the message, and the sender would not know who didn't receive the message." I think Kezzran has the answer but I thought the above maybe be of use.

On Wed, 28 Apr 2010 19:38:55 +0000, D.T. Jenkins wrote: >We are required to create a distribution group of approx. 18,000 members. Other than message size limits are there other best practices available to using a distribution group of this size? Are there any restrictions with exchange 2003 in creating a list this size? What release of Windows is being used to run the AD? And what's the forest and domain functional levels? Exchange doesn't manage the group membership, the AD does. I think you'll find that creating several smaller groups and then making those smaller groups members of one other group will work out much better for you. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP