In this article we'll continue talking about how to create a healthy email message and give a few tips how to survive anti-spam filters. Anti-spam filters catch every incoming email before it is delivered into the inbox and review it. They use a scoring system to classify an email as spam or legitimate. These filters (you might have heard about SpamAssassin, SpamProbe, or SpamCombat) look for certain patterns in the message, and assign "spam points" to it based on certain criteria: words, phrases, or even colors.

Depending on what these filters find or don't find in the message, points are added to or taken away from a scoring system. If the message score is 5.0 or higher, the filters add the *SPAM* word to the subject line of the message and the email is redirected to a “bulk” or “junk” mailbox. The lesser the score the better.

So, one of the main concerns when writing an email newsletter is to ensure that it is structured in a way that will allow it “pass” this test. I'll go to the point and give you a few tips you may follow:

1) Check what you put in the subject line

The subject line is one area of your e-mail that is carefully examined. For example, if you type a recipient's name in the message subject like “To: [recipient's name]”, your message will get 2.86 points because of this. If there is a lot of white space in the subject line, the email gets 2.64 points added to the score. The word FREE written in caps “weighs” additional 1.10 points.

If you put a date into the subject line, you can take off 0.48 points. And you can take one full point off if your subject contains a newsletter header!

2) Keep your message size from 20K to 50K

The size of the message does matter for anti-spam filters. The majority of spam emails are less than 20K. So, you can actually get 0.71 taken from your score if your message in within the 20K to 50K range.

3) Be wise with CAPS

If you use too many capital letters in your message, you'll get 0.21 points added to your score. So, use them wisely!

4) Use full hyperlinks

If you use a hyperlink in your email, make sure you put the http:// at the beginning. A spam filter will add 1.28 points to your emails if you don't!

5) Be restrained with colors

Different colors do matter too. Blue adds 0.21 points, red 0.33 points, and Magenta 0.44. The background color other than white adds 0.317 points to the message score. The Black is optimum as it won't add or take any points off.

6) Be a welcome guest

Send your recipients an e-mail after they have “opted in” at you site, and have them confirm that yes, you have permission to send the newsletters to them. This will help in the case if you need to prove you are not spamming, and that people want to receive the emails from you.

Have your recipients add you to their address books or white lists and your messages won't have to pass through anti-spam filters.

7) Beware of Blacklists!

Blacklists are databases of known spammers that ISPs regularly check. You may be added to a blacklist without you knowing it if one of your recipients clicks on the “this is spam” button. If you are blacklisted, contact the server provider immediately.

8) Test your message

Use a spam checker to test your message before you send it out to the world. A message content checker can help locate potential problems prior to distribution. It runs your receiver and sender addresses, subject line, and message content past a collection of rules. It then reports the result and tells you whether your message is likely to be filtered. Most checkers suggest a score of 5.0 will get your email sent to the spam scrap heap. One of our favorite free checkers is the Lyris' Content Checker. Lyris ContentChecker filters your message through several hundred Spam Assassin tests to determine if it has characteristics typical of unsolicited "spam" mail. Just fill in the blanks, including your email text or the full HTML coding, and submit it. You'll get an instant score on the next screen and a more detailed report by return email. This report highlights the factors used to evaluate your message, and may help you to make further improvements to it.

9) Don't use the “spammers” e-mail software

Anti-spam filtering systems are aware of some of the favorite email programs that professional spammers use and they add on as many as 3 points if you send the messages with those program. Be sure to check the ISP's “hit list” to see what email software are on it. Remember that the anti-spam filters are not perfect and they often happen to be “over protective”. They can give the “false negatives” and “false positives” results after the message analysis. A false negative is when a pure spam email gets through the filter, and a false positive is when a legitimate email ends in the “junk” box flagged as spam.

Around 150 companies now offer spam filtering software. The number of anti-spam techniques is growing and anti-spam technology is getting “smarter” too. For example, some servers (challenge systems) send an email back to the original sender and require a reply before they forward the email to the recipient. The idea behind this is that only a human can reply to a request for specific information. America Online recently announced a new spam filter that can actually “learn” the preferences of each of their subscribers.