This is the master list of all the Exchange 2007 objects, and the operating system won't let you mess with it.
Fortunately, there is a well respected work-around, create a new Global Address List, and then 'update' the mailbox. Here is a free tool to monitor your Exchange Server.
In the time it took to read the previous paragraph Lync Server should have synchronized and outstanding changes in Active Directory and Step #2 can be manually processed.
Be aware that is stuff is more process intensive than the automatic delta synchronization.This step should not be necessary under normal circumstances.If this is not the case or for some reason normal replication is failing then a manual process can be used to toss out the entire copy of AD information in the SQL database’s address book store and regenerate a completely new copy.To rebuild Lync’s copy of the AD data simply use the cmdlet.Research in the Exchange Management Shell with: get-Command *Global Address List Five verbs for Global Address List get, new, remove, set, and update.
For example: get-help new-Global Address List Note 1: As usual, Power Shell uses a singular noun: Global Address List Note 2: There is another family of cmdlets without the word 'Global', their noun is plain 'Address List'.
This polling interval is 5 minutes by default and can be customized to any value between 5 seconds and 3 hours.
Because Step #1 in the process happens by default every minute then any recent changes in AD should already be imported into the SQL database.
However, be careful, don't create too many lists, and furthermore, give thought to meaningful names for your lists.
The situation, you want to modify the GAL, however, you discover that you cannot edit (or delete) the Default Global Address List.
Download and install the utility, then inspect your mail queues, monitor the Exchange server's memory, confirm there is enough disk space and check the CPU utilization. Solar Winds provides this fully-functioning freebie, as part of their commitment to supporting the network management community.