What we’ve all been waiting for: An explanation as to why email messages are sometimes delayed when they are delivered to an Entourage client. (For those who do not know, Entourage is Microsoft’s Outlook client for the Macintosh.)

By default, Entourage is configured to use the equivalent of ‘Cached Exchange Mode’. This downloads items from the Exchange store on the Exchange server and stores them in a cache on the local Macintosh.

If this cache becomes corrupted, it can cause synchronization issues with the Exchange store – just like a PC running Outlook can.

The solution to try for this is similar for both platforms.
(You may want to create a backup of the local Exchange/Entourage/Outlook cache before you do this. Here’s a link to the MacTopia article explaining how to do this.)

On the Macintosh, Control-click (right-click on PCs) the folder you want to rebuild. Choose Properties.

There is a button labeled ‘Clear Offline Data’. Caution: Once you click this button, there is no verification step – the system just takes off and does it.

You will receive a notification that the offline data has been cleared when it is through.

Now, don’t panic. ALL of the items in that folder will have appeared to vanish. Simply quit Entourage (or Outlook) and then start it up again.

It will take a while, depending on how much data you have in your portion of the Exchange store, but your items will reload from the Exchange server and repopulate your folder.

Here’s a link to the ITPro article on Microsoft’s web site about this entire process.