Outlook Address Caching Issues
It is possible that after migration, some users may experience the following:
- Free/busy lookups fail on conference rooms and users.
- Email is bounced back to the sender with a message stating that the user cannot be found.
This is caused by the Outlook cache referencing addresses that are no longer valid. These addresses can be stored using internal legacy addresses that are no longer valid in Office 365. This may occur even if the entry appears to display the correct address. To resolve this issue, one of the following must be done:
- On a case-by-case basis, delete the address from the Outlook cached addresses using the delete checkbox on the right. Once deleted, re-enter the correct address and send again.
- Delete all cached addresses from Outlook. This will remove all cached entries and they will be re-saved over time as they are re-entered. To clear all items in the cache, select Options from the file menu in Outlook. In the Mail section of the Outlook Options page, click the Empty Auto-Complete List button.