If you send out e-mail newsletters regularly and suddenly get an unusually low open rate - you could be unknowingly triggering your reader's built-in email spam filters. What that means is that before your reader ever sees the email, it ends up in their Junk folder or Trash bin.

How can you make sure that your valid e-mail newsletter doesn't become a victim in the virtual circular file? By following these three simple steps:

1. Avoid "trigger words" - Trigger words are words that set off some e-mail program's built in spam-filters. Unfortunately, spammers have used some valuable words that would ordinarily make your visitors want to open your legitimate message - words like "free" and "money". You can find a list of some of the most common subject line and body text trigger words at http://www.andreaoneill.com/spamtriggers.html

2. Avoid spaces between letters or unusual characters - Let's say you really do have a free offer that will help your readers make money, and you really want to get that across to them. Some people do this by putting spaces or dots in between the letters - such as f r e e or fr.ee. Others substitute numbers for letters, such as m0ney.

Doing this might seem like a cute or innocent way to catch spam filters off-guard - if it were 1997. These days, the filters are more sophisticated and can catch tricky spellings and too many spaces. Instead, consider using different words such as "no cost" or phrase it a different way, such as "costs you nothing".

3. Conduct a SpamCheck - SpamCheck is a free service from a company called SiteSell. You simply send your newsletter to them and follow the steps on their web page to see if your email passes the SpamCheck test. You do not need to use the Site Build It services to take advantage of SpamCheck. It's free and can be found at http://spamcheck.sitesell.com

Alternatively, for just your e-mail address you can download a little software program called XMailWrite which will alert you if any of your words could set off the spam filter. It checks over 900 possible spam triggers, and is a good program to have on hand if you send multiple newsletters out. You can download it free at http://www.xmailwrite.com

If you keep these tips in mind when writing, you should drastically increase your email open rates without winding up in your visitor's junk mail bins. Good luck!