Anti-Spam & Anti-Virus

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In a recet study, spam costs US businesses $70 billion a year [1]. If you and your empoyees are still dealing a large volume of spam, you need to take some steps to protect your employee's productivity and use of time.

One of the most effective (and also easiest) measures you can take - when you have an in-house mail server - is to tell the server to block mail coming known spam sources. An RBL/DNSBL is 3rd party, typically non-profit organization that tracks known sources of spam. Spamhaus and SpamCop are two of thw more well-known such organizations. When your server receives an email, it checks with these websites to see if the it originated from a known source. If the source is listed, your server will simply ignore the message and optionally send a reply back to the sender saying like "Sorry your message was blocked by SpamCop...". This simple step alone will prevent 99% of spam from getting through. Optionally you can also block dynamic IP's since most spammers take over home users' computer with trojans and other malicious software and turn them into "zombies" for the purposs of sending out spam, ans since almost all home users use dynamic IPs, it would be a good idea to blcok SMTP traffic (the protocol for sending emails) coming from those addresses. The only requirement is that you need to have your in-house mail server.

If your email is hosted by a 3rd party host, you can still achieve significant reduction in the volume os recieved spam, by subscribing to a spam filtering service such as Postini. Alternatively, as a free option, many providers offer what is called a "Box Trapper". What this does is the first time you receive an email from someone, be it legitimate or a spammer, the server send a verification message back to the sender. If the sender is a real human being and verifies the message, the server adds his/her email and/or IP address to a safe list (a.k.a. white list). From then on, the sender can send you emails without re-verifying. Spammers never use thier real email or IP address and will never go through the trouble of verifying, so this is a safe method of getting rid of 99.9% of spam and little or no cost.

For larger organizations, it becomes necessary to combat the remaining 1% spam with software specifically designed for this purpose. McAfee and Websense make excellent products for this purpose.

Additionally, you can install spam and virus protection software on individual user's PCs and laptos, and this is necessary, at least as far as anit-virus, becasue not all viruses are propagates through email. Furthermore, no anti-virus softwre is guaranteed to catch 100% of malware. Therefore it is prudent practive to use server-based content filtering at the front end and use a different brand or protection on the desktops. Between these two measures, spam and malware can be almost entirely eliminated from the corporate environment.

Occassionally, despite all preventive measure, a vrius (typically a brand new one that has not been catalogued yet), will get through and infect one or more machines. When that happens, it is critical to let your support engineer know immediately so that those machines can be isolated to prevent spreading through the network as soon as possible. In these instances, your virus protection will most likely not raise any flags or warnings and it is up to the user to look for sign of compromise, e.g. pop-ups, slow performance, excessive network traffic and hard drive/CPU usage and bounced emails from users whom you never sent any email to.