Forwarding a message as an attachment is useful when you want to forward an email, unaltered, to another party. IT support may ask customers to forward an email as an attachment when investigating SPAM/Phishing attempts or diagnosing email deliverability issues.

The "Offline Global Address List" is used by Outlook to perform queries against the Global Address List without introducing additional strain on the Exchange environment. While this Offline Address Book is automatically updated every 24 hours, it can be manually updated from inside of Outlook.