How to Avoid Spam Filters

The single most important factor to consider with any email marketing campaign is the spamfilter. Businesses simply can’t afford to spend time, money and energy creating email campaigns only to have their emails land in spam folders. To bypass spam filters, it’s important to understand what they are and how they work. This guide gives you the rundown:

So, what exactly is spam?

The term ‘spam’ is usually used to refer to unsolicited emails sent to recipients in bulk. Spam may also be referred to as junk email or unsolicited bulk email (UBE) and is usually sent for commercial advertising (usually of dubious products or get-rich-quick schemes that recipients haven’t asked to receive), phishing (identity theft), or for spreading malware (malicious software, such as a viruses).

And what are spam filters?

Spam filters are programmes used to detect unsolicited and unwanted emails to prevent them from reaching users’ inboxes. Spam filters scan emails and evaluate them against a list of criteria in order to make a judgement as to whether or not they are genuine.

How does the spam filter work?

Sophisticated spam filters use a point system to evaluate emails and give them a score. If the score surpasses the threshold, the system automatically detects and reroutes the email into a dedicated spam folder.

The criteria threshold differs with each different server and, on top of that, the criteria is constantly developing and adapting in order to detect the latest tricks and techniques.

So, what exactly does the spam filter look for?

Spam filters analyse a range of data such as: the subject line, who the message is addressed to, content, your IP address, the sender and your domain name. Most sophisticated spam filters use a well-rounded combination of criteria in order to create a realistic judgement.

How do I avoid it?

There are a number of common mistakes to be aware of and steps you can take to avoid accidental spam filtering. Here are some of our favourites:

  1. Create a relevant and ‘spam friendly’ subject line. Avoid ‘spammy’ words and phrases such as ‘FREE’, ‘CLICK HERE’ or ‘BUY NOW’ and don’t overuse common punctuation such as exclamation marks or question marks. Avoid subject lines in capital letters as well as the excessive use of symbols as these will also be flagged up.
  2. Spam filters scan the entire content of the email for clues, so again, avoid ‘spammy’ words and phrases such as ‘Click Now to Download’, ‘FREE’ or ‘Guarantee’, and don’t overuse capital letters in the email. Always deliver what you have stated in the subject line.
  3. Ensure your email has a healthy balance of graphics and content. If you only need to display a simple graphic in your email, balance it with text by adding your company details and unsubscribe link in the footer area.
  4. Spam filters check for sloppy HTML (usually from converting a Microsoft Word file to HTML) so make sure your HTML coding is professional and doesn’t feature any broken images, missing tags or non-web-safe colours like bright red or green. It’s important to include a plain-text alternative with your HTML as an indicator of legitimacy to ISP’s and also to make your emails reader friendly.
  5. Avoid spelling mistakes. These are not only embarrassing but are also spam indicators so make sure all email content is thoroughly checked for accuracy.
  6. Don’t use video, Flash or JavaScript within the email and don’t embed forms in your emails. Instead, use subtle call to actions to encourage recipients to visit your website.
  7. Similarly, be wary of using attachments. Spam filters view them with suspicion as they are commonly used to spread malicious viruses. A prominently-placed call to action in your email, directing recipients to your website, may be more effective.
  8. Always provide a clear unsubscribe link. Don’t be tempted to obscure the unsubscribe link and avoid asking your contacts to complete a long survey or form before they are able to unsubscribe. Keep the unsubscribe process simple and straightforward.
  9. Send a test email to a list of test contacts. You can then analyse any problems that occur and fix them before sending your email out.
  10. To avoid your email being reported as spam, only send to recipients who have opted-in to receive emails from you.
  11. Some spam filters are particularly scrupulous and will categorise an email as spam if the email address can’t be found in the recipient’s address book, contact list or sent folder. Encourage recipients to whitelist your details (by entering details into a list of trusted contacts) and be sure to set up an email address featuring your company name and clear, verified field names such as ‘contact@’ ‘support@’ or ‘feedback@’.
  12. Carry out data cleansing at regular intervals to remove emails that bounce back. If bad emails accounts (ones that don’t exist, have been disabled or have full inboxes) are not removed, the spam filter will eventually penalise your domain or IP with a higher spam score, increasing the risk of your emails going straight to the spam folder.

How can I tell if my emails were spam filtered?

When you have sent your email out, you might be wondering whether your campaign has been successful. First, look at your open rate to see if it is consistent with previous email campaigns. If the open rate has dropped it may mean you have a spam filter problem. Another indicator is an abnormally high bounce rate.

If you are having problems with spam filters, there are a number of free online email spam tests you can use to try and find out why. These simple tests will provide specific reasons and information on why your emails may be getting filtered.

If you have any other tips or techniques on how to avoid the spam filter, please feel free to share them in the comments section below.