How to block IP addresses from port 25 [closed]

Solution 1:

What McAfee told you is definitely the recommended approach here. Spammers intentionally try direct connections for the exact reason you pointed out - they're trying to bypass perimeter defenses.

The specifics depend on your environment, preferences, and details from McAfee. Here are some links to get you started:

• https://documentation.cpanel.net/display/CKB/How+to+Prevent+Email+Abuse
• Prevent spamming
• Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?
• http://forums.cpanel.net/threads/stop-incoming-email-except-from-external-spam-filter.132385/
• http://www.exim.org/exim-html-current/doc/html/spec_html/ch-content_scanning_at_acl_time.html