iOS supports standard Mail protocols including IMAP, SMTP, and Microsoft Exchange ActiveSync 2007 and later. To learn how to set up iOS devices for use with a corporate email server, see the iOS Deployment Technical Reference Guide.
The following information from Microsoft's TechNet Library may also be useful when setting up or configuring Exchange servers for iOS mail access:
For Exchange 2013 documentation:
For Exchange 2010 documentation:
For Exchange 2007 documentation: