Using Microsoft Outlook, what is the limit to the number of addresses I can have in a personal distribution list?
The maximum number of contacts you can add to a personal distribution list within the Microsoft Outlook Address Book is roughly 60 to 120.
There is no specific maximum number of contacts because the actual limit is measured in kilobytes, not number of contacts. Exchange has an 8 KB limit on the contacts it can process. So if your contacts only consist of very short email addresses and names, you might be able to create distribution lists with more than 120 addresses. On the other hand, if your contacts contain large amounts of information, you might only be able to add 20 or so before you receive the error "This distribution list has reached the maximum size for your network e-mail server". The 60 to 120 figure is simply a practical average that has been observed over the years.
You can get around this limitation by using multiple distribution lists or IU List.
For more, see Microsoft support article 238569.
Last modified on August 27, 2012.