How to display SMTP info on Outlook Web App
If my memory serves me well, I believe I wrote about that a long time ago here at MSExchange.org. Here in this small Tutorial we go over the process on Exchange Server 2013/2016.
In the users’ options there is a place that provides information to the end-user how to connect using legacy protocols, such as SMTP, POP and IMAP.
Read more at source: http://www.itprocentral.com/how-to-display-smtp-info-on-outlook-web-app/