Anti-spam protection from Proofpoint now uses multiple methods to prevent spam from reaching the user's Inbox:
1. Rejection of email from computers on a 'Real-time Blacklist' of IP addresses known for sending spam or on networks designated by ISPs for consumer use.
2. Evaluating the permitted email content and assigning a spam score.
Email coming from computers on the 'Real-time Blacklist' will be rejected, and will not be seen in the Quarantine. Rejection of this category of email sender will result in smaller Mailguard digests and fewer spam emails in the system as a whole.
For technical purposes, Proofpoint will provide an error message with SMTP return code of 550 and the text "5.7.0 Local Policy Violation" to an email server on the Blacklist. This would alert a system admin at the sending site of a rejection by our Mailguard system.
Standard spam content evaluation will automatically delete email above a certain score, depending on the policy chosen.