If you are using one of our groupware collaboration solution such as Team Helpdesk or Team CRM, which uses a centralized repository (a shared mailbox folder or a public folder) to store the tickets, invoices etc, the way you had configured your Outlook to connect to your Exchange server may affect the overall performance. Outlook provides 2 modes of connection to Exchange – Cached Exchange mode and Online Mode.
Cached Exchange Mode was introduced in Outlook 2003 to give users a seamless online and offline Outlook experience. It also insulates users from network latency and connectivity issues while they are using Outlook. By caching the user’s mailbox and the OAB locally with Cached Exchange Mode, Outlook no longer depends on continuous network connectivity for access to user information. While connected, Outlook continuously updates users’ mailboxes so that the mailboxes are kept up-to-date. If a user disconnects from the network—for example, by removing a portable computer, such as a laptop, from a docking station—the latest Outlook information is automatically available offline.
Online Mode works by using information directly from the server, and, as the name implies, it requires a connection. Mailbox data is only cached in memory and never written to disk.
In context of Team Helpdesk and Team CRM, we recommend ‘Online mode’ if you and your team members are always connected to your in-housed Exchange server. If you are connected to your exchange server remotely, or if your Exchange server is hosted on the web (like Office 365 Exchange Online), then we recommend that you use the ‘Cached Exchange mode’ connection. However, you should ideally test out both connection mode and decide which connectivity mode, Cached Exchange Mode or Online Mode, is appropriate for your environment.
To understand more about these two modes of connection to Exchange and which one to use, refer to this excellent MSDN article – Choose between Cached Exchange Mode and Online Mode for Outlook