First off, lets clarify what exactly spam is, the Oxford Dictionary describes spam as irrelevant or inappropriate messages sent on the Internet to a large number of users.

Spam is a major issue affecting everyone on the internet. I’m sure none of us particularly enjoy receiving spam but most of us are content to simply press delete and get on with our day. What we do find more of a problem is when genuine emails we send out mark us as spam to our customer base!

Today, more and more words and phrases are being flagged as "spam" words by various email programmes, and thus will automatically block messages using them too often. This is because many anti-spam systems rely on keywords for determining whether an email should be considered spam. These programs assign spam probabilities to each word, so that some words are weighted as more likely to signal spam than others. If the overall email contains a high proportion of spam words, or if it passes a certain threshold of spam words, it is more likely to get trapped in anti-spam filters.

Unless you are careful in using the words and phrases, important business emails or marketing campaigns could end in the spam folder of the recipient.

Avoiding use of known spam words is a key step to getting your message through the over zealous spam filters that some companies use. Apart from this, my advice would be to try not to repeat words, not to use all caps (upper case) and try to minimise use of !, $, or 100% and other  punctuation marks.

Below is a list of some of the words and phrases that have been known to trigger spam filters, Trying to avoid multiple use of these words in your campaign can help prevent your email get stuck in the spam filters.

For further information about creating a good email marketing campaign, take a look at this post