Hi, I have exchange server 2010 in my organization. we have 3 dynamic distribution group i.e all staff, Sydney staff and Melbourne staff. 

The problem is whenever I add new email to exchange its not getting updated into the Sydney staff dynamic distribution group but gets updated in all staff dynamic distribution group. The new email I added are the users from the Sydney organization unit in ADUC and should get updated into Sydney staff dynamic distribution group.

All the previously configured email are present in the Sydney staff dynamic distribution group and can receive email.

So what should I do to make Sydney staff dynamic distribution group to automatically update users when configured.

Are you sure that the new users have whatever attribute is required in the Sydney Staff dynamic group for them to be included? Post the query the group uses here so we can see.

yes, the dynamic distribution group was created in such a way that all the staff in the sydney OU with email id can receive the email. until recently one of the new staff complained that she did not receive the sydney staff email.

So, when I checked the preview button in sydney staff dynamic distribution properties(properties ->filter ->preview), i cannot see any newly joined staff member name. These members are located in the sydney  OU in ADUC.

This is the filter applied to sydney DDG

((((RecipientType -eq 'UserMailbox') -and (Office -eq 'Sydney'))) -and (-not(Name -like 'SystemMailbox{*')) -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq 'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')))

((((RecipientType -eq 'UserMailbox') -and (Office -eq 'Sydney'))) -and (-not(Name -like 'SystemMailbox{*')) -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq 'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')))

Your query says different to what you have said. The query for the group is looking for 'Sydney' in the Office field. It is not looking at the OU where the users are.  Make this change to the user accounts, and you should see them in the DDG.

thanks Peter