quarantine emails send to multiple users from outside

[jebujohn]

We get spam emails with over 200 of our users copied on a single email from a variety of gmail addresses with subtly different subject lines. 

Is there a way to create rules to move emails from outside the organisation to quarantine if they are sent with more than a fixed number of users as internal recipients?

I know this is an edge use case but thought I would check

Best wishes 

Jacob

[#2]

There is no ideal solution for this.
The closest you can get to avoiding Bulk Emails is by setting Bulk email threshold in Anti Spam Policy. But will that help you? depends on the BCL value of the email.

[#3]

Not natively. You have to create a so called "transport agent" (a piece of software) to do that,