Finding Unused Proxy Addresses for Exchange Online Mail-Enabled Objects

A request came in about how to find unused proxy addresses for Exchange Online mail-enabled objects. There's no out-of-the-box report available for proxy address usage, but we can solve the problem by using a PowerShell script to download historical message trace data to check every proxy address for all mailboxes against. The question then is what to do with the unused proxy addresses?

https://practical365.com/find-unused-proxy-addresses/