Why is SpamAssassin not scanning certain emails?
There are a few common reasons SpamAssassin would not scan a certain email. To check whether SpamAssassin scanned the email in question, you can refer to the exim_mainlog. If you run a command such as:
grep Exim-ID /var/log/exim_mainlog
*you would replace Exim-ID with the Exim ID of the email in question
An email scanned by SpamAssassin would contain an entry such as the following:
SpamAssassin as $USER detected message as spam
SpamAssassin will not scan an email if the email's sender is added as a "Trusted SMTP IP Address" in WHM > Exim Configuration Manager > Access Lists. Additionally, if the size of the email is larger than the SpamAssassin size threshold set within WHM > Exim Configuration Manager > "Apache SpamAssassin Options", it will also be skipped. Lastly, SpamAssassin will skip scanning local email sent from a sender to a recipient on the same server.