As of January 29, the Division of IT disabled the ability for email clients to connect to the Exchange servers using POP. POP is used by some local email clients to retrieve email from a remote server. The POP protocol increases vulnerability to spam attacks and few faculty/staff use POP.
POP has been discontinued primarily because, by design, POP causes email to be moved off the University’s email servers and onto the user’s computer. The University is obligated to comply with a variety of legal and policy requirements, including maintenance of official records, responses to open records requests, and other legal processes. Eliminating POP allows the University to more easily adhere to these record management requirements.
The Division of IT has contacted POP users and recommended they receive email via a web browser (e.g. Firefox or Internet Explorer) at http://webmail.missouri.edu.
— Jan. 28, 2014