When changes occur within the main Global Address Book (GAL) on the Office 365, computers running Outlook 20/2016 may not automatically receive the updates.If this is happening, then you may notice missing, non-existent and/or incorrect entries.Synchronizing your Outlook (cached) address book with the Global Address book may fix these discrepancies.
Microsoft also has some great training videos you can watch to become familiar with using Office 365 applications.
A Microsoft Outlook Most Valuable Professional (MVP) since 1999, Diane is the author of several books, including Outlook 2013 Absolute Beginners Book.
Before emptying the cache, you may want to back up your Outlook information that is stored only locally on your computer.
For more information, see Export or manually archive Outlook items.
The OST Integrity Check Tool (Scanost.exe) is installed when you installed Outlook, and it’s located in the following locations: Outlook 2003: :\Program Files\Microsoft Office\OFFICE12Resolution 4: Work Offline and Online Sometimes, simple step may help to resolve some simple issue.