Whenever a user sends an e-mail to a Dynamic Distribution List, Exchange queries Active Directory to get an updated list of all the recipients that are part of that DL. Unfortunately, Address Lists are not like that, even when accessed through OWA...
The problem is that when a new Exchange recipient is created, the Microsoft Exchange System Attendant will make it a member of any Address Lists it should be a member of. However, when a user is updated (and should be part of another Address List instead) we need to manually update the old Address List so the user gets removed from it and update the new Address List so he/she gets added to it...
Changes that we make to an address list aren't applied to recipients until we apply the list. We can apply changes to address lists immediately or at a scheduled time by using the New Address List wizard or the Edit Address List wizard.
The easiest way, however, is to run the following cmdlet to update all the Address Lists:
Get-AddressList | Update-AddressList
If you just want to update a particular Address List, then you can use the following cmdlet: