Information
Originators of spam messages are constantly changing their techniques in order to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms.
Exchange 2013 provides both antispam and antimalware protection out of the box. The Exchange 2013 antispam and antimalware product capabilities are limited but still provide some protection.
Solution
Update the EDSP.
Open the Exchange Management Shell and enter the following command for any values that were not set to True:
Set-ContentFilterConfig -Enabled $true
Set-SenderFilterConfig -Enabled $true
Set-SenderIDConfig -Enabled $true
Set-SenderReputationConfig -Enabled $true