Hi AllWe are running Exchange 2003 SP2 on Windows 2003 SP2 servers.I have a Distribution Group ona server that has about 5500 users (all internal and within our domain).I'm wondering if this is too many and we need to split the DL into sub-DL's. Does anyone know if there is a recommended limit on members of a DL in Exchange 2003?Cheers

Hi,I believe 5500 users is not really a very huge number for Exchange and AD to handle. However the recommendation is to have the users distributed across several small distribution lists and then have them nested within each other. This helps in assigining a correct expansion server for each of the DL if you have a spread active directory and exchange server topology. I am not aware of any limits as such. Additinally, if you have a very poorly performing global catalog server in some site you should not create a DL with too many users in it. This will difinitely count in performance in peak hours. M-Milind Naphade

Yoshi, See this KB, http://support.microsoft.com/kb/238569This is a limitation of distribution lists that are created and stored in a Microsoft Exchange Server mailbox store or in a personal folders (.pst) file. There is no definite limit to the number of contacts that you can add to a distribution list. The exact limit is based on the total file size of the contacts. If you use only the very basic information for contacts, your distribution list limit may be as many as 125 contacts to 130 contacts. For example, the information for the contacts in a list of this size may include only the name and the e-mail address for each contact. You can create very large distribution lists that contain over a 1,000 contacts. However, these very large lists may not function as expected in Outlook. For best results, the typical number of contacts that you should add to a distribution list is between 50 contacts and 70 contacts. However, if the contacts contain lots of information, the distribution list limit should be as small as 25 contacts. Additionally, the distribution list limit is based on the property size limit of the computer that is running Exchange Server. The property size limit for an Exchange server is about 8 kilobytes (KB). The Exchange server stores all contact links in one property store. Therefore, the distribution list limit also depends on the average length of the contact's name and the average size of the entry ID. The size of the entry ID depends on the type of e-mail address and the length of the message. Mark Morowczynski|MCSE 2003:Messaging, Security|MCITP: Enterprise Support|MCTS:Windows Mobile Admin|Security+|http://almostdailytech.com

Here is no limitation to the size of the distribution group (DG) that you can create in Exchange 2003 Standard or Enterprise. If AD can hold a DG of 10000 users or more, exchange will use it properly, the only issue may be a slight latency but this should only affect a few users Former recommended number for the DG in the AD on Windows 2000 or Windows Server 2003 at a forest functional level of Windows 2000 is 5,000. But, starting with Windows Server 2003 forest level, testing in this area has yet to reveal any new recommended limits to the number of members in a DG. Production environments have been reported to exceed 4 million members, and Microsoft scalability testing reached 500 million members ------------<Active Directory Maximum Limits>