Our SBS2011 on-premise anti-spam will be soon discontinued. The manufacturer suggested us:
For an alternative solution, we recommends Exchange Online Protection.
Can we use Exchange Online Protection with MS Exchange 2010 on premise? If not, is there any other -on premise- anti-spam tool we can purchase or shall we all migrate to Exchange Online at some point?
EOP can be used with on-premises Exchange solutions.
Technically what happens is that you point your MX records at EOP, and then set up an outbound connector from EOP to your on-prem server(s). You can also use EOP for outbound filtering by using them as a “smart host”.
The same principle applies to other cloud-based or on-prem anti-spam solutions.