In past versions of iOS, you can easily set up with services like iCloud, Exchange, and Yahoo. Logging in will let you activate all their services like calendar and mail. With iOS 10 you can do this same thing with macOS server. Thanks to The Brooks Review for finding this new option. 

In Settings, choose Mail -> Accounts -> Add Account and you'll presented with these options:

It's unfortunate it's not right there, but you can choose "Other" for a couple more options:

Choosing "macOS Server Account" will prompt you to add the information. Simple add the IP or hostname and then your username and password:

Your phone will quickly log in and present to you all the services that are available on the server:

All of the above options can be quite useful when you're looking to keep your data on a server that you own. VPN is especially great when you're on the road and want to protect your data. However, File Sharing is there and can be enabled but I have no idea where it's accessible. If you know, send us a note on Twitter at @Macstadium. 

Update -  A helpful tweet from a customer:

@BenjaminBrooks@brianstuckiYou must use an app that can switch file picker location. Readdle Documents works.pic.twitter.com/OHPNK3xRbC — Athanasios (@athanasiosa)September 13, 2016

Many of these services can be added by your IT staff remotely if you are running an MDM server using Profile Manager. But if you run a server to manage family lists or a small business, and each person brings their own iOS device, this is a quick way for them to get all of their services up and running quickly.