All of your emails are located on a Microsoft Server. When you access Outlook on the cloud, you are simply downloading emails from Microsoft and caching (saving offline) the contents to your Abacus server. Outlook has a feature that allows you to choose how much of that email you wish to save. We recommended that you set this value to 3-6 months so that you are not downloading years worth of email. If you do not have cached exchange mode enabled or the settings are set to download ALL email, you will notice a significant slowdown when using Outlook.
To speed up your Outlook and to reduce huge mail files, use cached exchange mode.
APC users who use Outlook inside the cloud.
You must have an email account and license that is compatible with Outlook.
Within Outlook, go to File > Account Settings > Account Settings.
Go to the E-mail tab, then select Change.
Check to turn Cached Exchange Mode on, select the time frame you would like to have cached, and then Next/Finish out of this dialog box.
Close and re-open Outlook. This will re-configure your cache.
It will take some time for your Outlook to re-build your local cache, but you can start using it right away.