Moving away from a Cloud E-mail Archiving Provider?

M Boyle wrote:

These days I'd shove the whole sodding pile into Office 365. Archiving and Exchange. Let MS deal with it. 

I'd like to do that, but our mail server has to be ITAR compliant, which is part of the reason for hosting in-house.  If memory serves, MS can do that but at a very large price (more than we would pay).  But, I do not believe the archive need be compliant.