Configure the anti-spam policies
Spam filtering is automatically enabled company-wide through the default anti-spam policies (connection filter, spam filter, and outbound spam). As an administrator, you can view and edit, but not delete, the default anti-spam policies so that they are tailored to best meet the needs of your organization. For greater granularity, you can also create custom policies and apply them to specified users, groups, or domains in your organization. By default, custom policies take precedence over the default policy, but you can change the priority of your policies.
For more about configuring your anti-spam policies, see the following topics:
For EOP standalone customers: By default, the EOP content filters send spam-detected messages to each recipients' Junk Email folder. However, in order to ensure that the Move message to Junk Email folder action will work with on-premises mailboxes, you must configure two Exchange mail flow rules (also known as transport rules) on your on-premises servers to detect spam headers added by EOP. For details, see Ensure that spam is routed to each user's Junk Email folder.