Yahoo’s mail service reminds us that spammers write to many people who don’t want their mail, so their anti-spam filters are designed to identify that behavior. One of the patterns they consider in identifying a spammer is too high a percentage of respondents that choose to move the email to the spam folder.

To avoid being perceived as a spammer, don’t send out one email to all people containing many different messages intended for different groups of people. Filter that list to send only the pertinent information out to the right people in each email. Recipients would rather receive two emails with separate messages where both pertain to them, than one long email with a mishmash of information, some of which has nothing to do with them.

One of our clients had an email treated as spam by more than one of the large internet mail providers because she included the phrase “Free tickets”. It was a totally legitimate offer she was making to her people, but too many spammers have used similar wording.

Sendgrid.com tells us that “Unfortunately, there is no complete list of spam trigger words. Further, it is not always the case that your email will end up in the spam filter simply by using a so-called trigger word. The key thing to remember is that a spam filter is trying to remove commercial advertisements and promotions. So generally, words that are common in such emails should be avoided or used sparingly.” There are a variety of sites that detail spam trigger words and phishing phrases to avoid in subject lines.

So, if your email gets past the spam filters, you still have to prevent it from being mistaken for spam or unnecessary information and deleted without so much as a glance.

Mindtools.com suggests that we treat subject lines a little like newspaper headlines. “A newspaper headline has two functions: it grabs your attention, and it tells you what the article is about, so that you can decide if you want to read further. Email subject lines need to do exactly the same thing! Use a few well-chosen words, so that the recipient knows at a glance what the email is about. Of course, just as it would be ridiculous to publish a newspaper without headlines, never leave the subject line blank. Emails with blank subject lines are usually spam!”

Mail Chimp analyzed over 40 million emails sent from customers and found that 9 of the top 10 highest open rates had the company name in it

Examples:

In general, .jpg, .gif, .png and .pdf attachments are safe to send, provided you include some content in the email as well. However, executable attachments such as .exe, .zip, .swf, etc. should be avoided entirely.

TechRepublic.com suggests “Don’t attach large files to an e-mail; anything over one or two megabytes shouldn’t be sent via e-mail. E-mail attachments consume inordinate amounts of e-mail server space and network bandwidth and are often the culprits behind virus outbreaks.” Because of their link to viruses, emails containing attachments can have a greater chance of being treated as spam if other elements of the email are similar to spam. Many sources online agreed with limiting the file size of attachments, not only in a single attachment but as a total as well. Some email inboxes have limits to their capacity; emails with large attachments can claim too much space to be kept.

Spammers list typically have a larger percentage of bad email addresses than legitimate lists. One great way to look like a spammer is to include bad email address in your bulk emails, especially when you keep sending to that address.