A Cached Address is an email address that has been saved by Outlook when you last sent to it. This appears when you begin to type the email address into the 'To' field when composing an email.
When using Outlook it is possible for cached entries to become corrupt. This is usually caused by a change being made to the destination mailbox, for example the mailbox being moved or deleted and recreated. This will mean that when sending to such a mailbox using a cached entry, it will attempt to deliver the email to the old destination. This will result in a Non-Delivery Report (NDR) being generated.
Remove a Single Cached Address
The entry will be re-created when you next send an email to that address.
Remove All Cached Addresses
This will remove all Auto Complete entries for that Outlook profile.