Blocking incoming SMTP traffic from all except one server DrayTek2019-09-13T07:17:03+00:00December 12th, 2011|Firewall & Content Filtering| And allow access to a single PC on the LAN Source address (Mail Server) Destination Server Port 25 Share This Story, Choose Your Platform! FacebookTwitterRedditLinkedInWhatsAppTumblrPinterestVkEmail