Order of SMTP and SMTPS spam filtering

Chapter 15 Unified Threat Management for FortiOS 5.0 : Email filter : Email filter concepts : Order of spam filtering : Order of SMTP and SMTPS spam filtering

The FortiGate unit scans SMTP and SMTPS email for spam in the order given below. SMTPS spam filtering is available on FortiGate units that support SSL content scanning and inspection.

1. IP address black/white list (BWL) check on last hop IP

2. DNSBL & ORDBL check on last hop IP, FortiGuard Antispam IP check on last hop IP, HELO DNS lookup

3. MIME headers check, E-mail address BWL check

4. Banned word check on email subject

5. IP address BWL check (for IPs extracted from “Received” headers)

6. Banned word check on email body

7. Return email DNS check, FortiGuard Antispam email checksum check, FortiGuard Antispam URL check, DNSBL & ORDBL check on public IP extracted from header.