We have started moving clients to a setup where we use a single name for all Exchange servers (i.e. mail.domain.com). So ActiveSync/OWA....etc all use the same domain name. For Autodiscover we use a SRV DNS record this allows us to use activesync/outlook anywhere fine.
We have been using this for a few years now without issue but recently we ran into issues with Outlook 2016... Specifically with a non-domain computer, we cannot seem to get Outlook to connect to Exchange using a Non-domain PC and if I understand it correctly is because Outlook 2016 connects to Exchange different, it no longer allows us to manually enter proxy settings.
Seems to me that a computer not on the domain using Outlook 2016 should still be able to connect to Exchange... but I cannot seem to figure it out. (we are using Exchange 2013 SP1 CU14)