However, when the Outlook client fails to synchronize the changes stored in the Outlook data file or OST with the mailbox on the server, the changes are not reflected in the OWA. All the changes are made directly on the mailbox server, and thus, changes are updated in real-time. On the other hand, Outlook Web App or OWA runs on a compatible web browser, such as Google Chrome, and connects to the mailbox server directly. The changes made in the Outlook client are first stored in the OST file and then synched with the Exchange or mailbox server based on the Outlook settings. Offline Storage Table or OST (also known as Offline Folder) allows users to access their Outlook account and mail items even when the system is offline. Outlook for Windows creates an Outlook data file, such as OST, to store a copy of mailbox items on the local machine. Outlook client and Outlook Web App (OWA) are two different modes to access Exchange or Microsoft 365 email accounts. In this post, we discussed reasons for synchronization issues between Outlook and Outlook Web App, solutions to fix them. It also prevents Outlook users from sending or receiving new emails on Outlook clients.

Synchronization issues between Outlook and Outlook Web App can lead to outdated mailboxes and discrepancies between the Outlook client and OWA.

Mac mail exchange folders not syncing