Best practices in email marketing constantly evolve to reflect ever-changing online behavior. It’s important to stay current with the latest email protocols in order to optimize campaign effectiveness and maintain the most positive relationship with your campaign recipients.

For this reason, we’ve put together an updated list of things that you might consider doing (or avoiding) when creating and sending your email messages. Following these guidelines can improve the effectiveness of your campaigns by increasing your inbox delivery and click-through rates and minimizing negative outcomes such as unsubscribes or spam complaints. Some of these can also help to improve or maintain your sender reputation.

This week we will quickly discuss a variety of tactics that you should avoid in your emails. Staying away from these “Dont’s” will help you make a more positive impact in your recipients’ inboxes.


  • Use attachments in your messages.
  • Link to “executable” files like .exe, .zip, .swf, etc. This is likely to cause your messages to get marked as a “phishing” email by spam filters, and placed in the Spam folder or even quarantined.
  • Use JavaScript in your content. Most email clients will block JavaScript or strip out that code entirely. As a result, your email may not display as intended and could even be placed in the Spam folder or quarantined.
  • Link to external stylesheets – most email clients will block them.
  • Use loud colors in the email body text, such as pure red or green. This can come across as “yelling” at your recipients, trying to attract their attention to an area of your message, which is something spammers tend to do.
  • Use all capital letters in the subject line or overuse them in the body of the message (same reason as above).
  • Use exclamation signs or other punctuation marks more than once (same reason as above).
  • Use excessive symbols – use descriptive words instead. When you use dollar signs, make sure you don’t overdo it ($$$).
  • Use the word “test” in the subject line, or “dummy” text, like Lorem Ipsum, in the body of the message, even when sending a preliminary version of your message for review. Both could cause your message to go to the Spam folder.
  • Use spammy words or phrases unnecessarily, like “mortgage”, “act now!”, “click here!”, “limited time”, and “guaranteed”.
  • Get “creative” with your spelling, like “FR33”, “m0rtgage”, “MON3Y”, etc., especially in the subject line. Spammers do this to try and trick Spam filters, so they’re programmed to look for them.
  • Use “corporate” or “official” phrases in your unsubscribe links, like “…to stop further distribution”, or “To prevent future messages from being sent…”. That type of phrase could end up triggering Spam filters. And an unsubscribe link that says anything like “…you registered with a partner” will greatly increase your chances of going into the Spam folder because it’s an indication that your list isn’t permission based.
  • Use the word “Dear” when addressing your recipients, as in “Dear Reader” or “Dear Mary”. This will increase your Spam score.
  • Display full URLs in the body of the HTML version of the message. Instead, use a text string like “visit our website” that includes the HTML link underneath it in an anchor <a> tag.
  • Use shortened URLs – spammers use them to hide the domain they’re linking to.
  • Use a domain in your message content that’s blacklisted. You can use a site like to check whether a domain is on a blacklist.
  • Use ‘Re’ or ‘Fwd’ in the subject line to trick recipients into thinking that your mail is a continuation of a previous conversation.

NOTE: Using a misleading subject line is a violation of CAN-SPAM and other Spam laws.

  • Offer misleading or unsubstantiated claims in the subject line or message.
  • Use purchased lists. Sending emails to those who don’t expect them is risky and can put your company’s reputation at stake due to excessive negative engagement like Spam complaints, unsubscribes, unread messages, etc.
  • Use bad/broken HTML coding in email, like missing tags, content below the </html> tag, and empty tags (like the <title> tag, which is inserted automatically by some WYSIWYG editors). Keep HTML coding as simple as possible (e.g. avoid things like nested tables).
  • Convert Microsoft Word files to HTML – even the best conversion tools could miss some of Microsoft’s proprietary or hidden tags, which could cause your messages to be displayed incorrectly, or even get them mistaken as a phishing message or placed in the Spam folder.
  • Use a single, large image in your message. This practice is used by spammers to hide their content from Spam filters. Aim for 60% or more text and 40% or less images, and break larger images up into at least two smaller images.

Make sure to check in next week when we dive into the many suggestions that you can and should do in order to improve your inbox rates.