Occasionally users have large GALs and the GALSync program may error when trying to get the initial sync and since it is being denied access to the objects by Exchange, it automatically excludes the items. Messages in the Add2Exchange log will confirm this.

After the initial sync the program only replicates changes or "Deltas", but the first sync evaluates everything.

Sometimes this process will expose some objects which are programmatically inaccessible. Examples of these are objects like Contacts which were created in Exchange 2003 or 2007 and have not been upgraded to the newest Exchange version management, so when opened in ECP or EMC and you momentarily hide and unhide them or view the Exchange Tab, they will error with a screen which tells that it must be upgraded. Other examples are any objects which have a space in the Alias. Correcting these objects will make the process smoother. Use Exchange Management Console to investigate the properties of the items listed in the log. If nothing is obvious after an "all tab" inspection, try to hide it and apply, and then unhide it. This usually triggers an issue if there is one. It is best to fix these objects anyway and clean up the prior migration and upgrade them to the latest management or fix the aliases with spaces.

If any of these are found, then try again to include those objects you wish from the A2E Console and run the GalSync by closing the Console and starting the Add2Exchange Service, check again the event logs in 15 mins or so. If you continue to have issues, see below.

When we installed Add2Exchange, we created a policy to enable the service account, typically "Zadd2Exchange" greater power, and act like a service account. If you have this kind of problem, you may have an issue with AD/Gal throttle and A2E reports that the id of items can’t be gotten for inclusion or exclusion in the GAL. If this happens, then items will get auto excluded from the GAL cache – so you would have to reinclude them after running this from the Add2Exchange Console, Global Settings, Gal Settings, and Exclusions.

Occasionally, this change needs to be added to our default Throttling Policy:

Set-ThrottlingPolicy A2EPolicy -RCAMaxConcurrency $null -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSPercentTimeInAD $null -EWSPercentTimeInCAS $null -EWSPercentTimeInMailboxRPC $null -EWSMaxSubscriptions $null -EWSFastSearchTimeoutInSeconds $null -EWSFindCountLimit $null

Set-Mailbox "zadd2exchange" -ThrottlingPolicy A2EPolicy
- Where you would replace your service account name from zadd2exchange.

Test it 90 mins after running the commands above. If this doesn't work, continue to the next section.

Finally, sometimes the maximum objects are reached and these commands would need to be added, Excerpt from Microsoft KB article 830836.

On the Exchange computer, click Start, click Run, type regedit in the Open box, and then click OK.
Locate and then click the following registry key:
On the Edit menu, point to New, and then click Key.
Type MaxObjsPerMapiSession, and then press ENTER.
For each object type that is listed in the event ID 9646 message (e.g. objtMessage and objtAttachment), follow these steps:

On the Edit menu, point to New, and then click DWORD Value.
Type the object name (for example, type objtMessage), and then press ENTER.
Press ENTER again to open the Edit DWORD Value dialog box, type 1500 in the Value data box, and then click OK.
Close Registry Editor.

Try your test again.