One thing I missed with on-site Exchange was the ease that the data could be backed up,
I previously used a powershell script that extracted users data from the Exchange database every night into a .pst file. This file was then put into a folder that was backed up along with the users other data.
When I moved to a hosted email/calendar, the only way to export the calendar was to logon to the web interface & click a link which downloaded an .ical file. This was all a bit manual and I wanted something to automatically do this at least once a week.
It was a requirement to get the Information Radiator calendar working that I created a single .ical of all the calendar events regularly, so it was easy to occasionally intercept a copy of the .ical & place it on a backed up area of the server.
I download emails using the Python program ImapGrab.py (https://sourceforge.net/p/imapgrab/wiki/Home/) & I put these in the same location as the calendar download, ready to be safely backed up with the rest of our data.