Does email syncing using MS Exchange exchange work in a similar way to Dropbox such that a change made on the local drive automatically syncs with the cloud version of that file? Or is it one way only from the cloud to the local drive?

So for example I have an OST file on my local drive which is synced to the cloud using MS Exchange.
The OST file on the LOCAL drive gets encrypted by Wannacrpt. Will the email stored in the cloud also become encrypted? If yes, is it possible to roll back to previous un encrypted versions of those emails?