About FirstClass Internet Services security Handling spam Handling relaying Controlling unwanted outside connections (DoS attacks) Sending secure mail Controlling system viruses Internet Services supports a variety of powerful security features to protect your system from system abuse, such as annoying spam, unsafe SMTP relaying, Denial of Service attacks (DoS), and viruses on mail attachments. Several default behaviours, the reworking of the UCE/Spam tab on the Basic Internet Setup form, and additional options on the Internet Services Monitor, make it easier to stop spam and to provide safe SMTP relaying. Below is an overview of new and enhanced security features and a review of existing ones grouped according to their functions. Top Handling spam You can control and manage spam on your system (see Handling spam) using these options: • use and customize documents in the Filters folder • filter documents • rules.AttachmentBlock • rules.SubjectBlock • defining your own blocking lists • rules.MailRules • Realtime Blocklists (RBL) and Spam URI Realtime Blocklists (SURBL) support • caching RBL/SURBL hits • DNS lookup (check the IP address of servers trying to log in to your site) • crossposting limits for messages • customize user-created mail rules using automatic mail handling (see Client help). Top Handling relaying You can control relaying on your system by totally disallowing relaying on your site or providing only certain users or groups to relay (see Handling relaying). Top Controlling unwanted outside connections (DoS attacks) A DoS attack occurs when your system is bombarded by so much traffic (bad connections) that legitimate sites or users can't connect. You can control unwanted outside connections using these options (see Controlling unwanted connections): • reject or accept connections based on IP addresses in your filter documents in the Filters folder • register strikes against your system from SMTP servers that repeatedly attempt to deliver spam to your site • suspend connections (IP addresses) in a temporary blackhole • password attack detection using SMTP AUTH (Internet Services performs this by default) • monitor system abuse and configure Internet Services to trigger warnings from unwanted connections from the Internet Services Monitor. Top Sending secure mail You can send encrypted mail by using S/MIME messages (see Sending secure mail). Top Controlling system viruses You can check Internet mail for viruses using Symantec AntiVirus scan engine (see Controlling system viruses). Top