Outlook web excessive bandwidth usage

[Marconi]

Hello,

We recently noticed starting last few weeks that application (outlook-web-online) had a massive data being sent and saturating our internet link.

This looks to be across the network as we can identify multiple users with same application traffic being the top bandwidth consumers when we generated the custom report.

Does anyone experienced the same issue? 

[Marconi]

Yes, weird thing is that I'm observing it for few weeks now and it seems like it never stop syncing.

[Mario_Arendse]

I have seen this - but strangely only from sites that have a VM-Series Palo Alto.

I came here for possible resolution, but looks like I need to search further.