If they do POP, the mail will be kept in a PST. With Outlook everything else like the calendar, contacts...is also kept in that same PST.
Old versions of Outlook, Microsoft had a PST backup plug in for Outlook
https://www.microsoft.com/en-us/download/details.aspx?id=9003
It still works in 2010 (to the best of my knowledge)
https://www.msoutlook.info/question/421
and another link to a trick to get it to work in 2010
https://support.microsoft.com/en-us...lders-backup-add-in-to-work-with-outlook-2010
I highly advise you do not move the working PST across the network..that is a big no-no. Microsoft even advises against it. Outlook and its PST have a very heavy relationship..and the bigger the PST...it's a huge load. Does not do well across networks. Add antivirus scanning to it, slow disk..and..yeah, it's just bad. Likely will not back up properly either from the servers backup.
Use backup software to make copies of the local PST across the network as a backup.