Guide to Sending Emails and Avoiding the Junk Filter

Mar 23, 2012

Some simple rules to follow when creating and sending promotional emails.  This does NOT guarantee that your email will not be flagged as junk but it will help with some common triggers and know issues.

Guide to sending email and not being spam or junk


  1. Avoid using these trigger words in the body or subject line: Marketing, Market, Free, Bonus, Click, Click here, Advertising, Advertise, Ads,  Sales, Sell, Selling, Shop, Shopping, Package, Buy, Purchase, Mortgage, Finance, Refinance, Free Trial  

    More words to avoid

  2. Don't use BCC distribution to more than 10 names. If you do so, it's likely that you'll be tagged as a spammer. Send individual messages to each recipient 

    It is better to send an individual message to each recipient, rather than using multiple addresses in the BCC field because many spam filters (and many ISP's) automatically flag multiple recipients as spam.

  3. Avoid sending attachments. Attachments can carry viruses and are frequently filtered out pro-actively.

  4. Include an easy means for recipients to remove themselves from your email list. Also ensure you have a privacy policy which can be easily found on your website.

  5. Use normal conversational language; be sure not to use excessive spacing and or capitalization on your subject. Do not use "cute" spellings, Don't S.P.A.C.E out your words; don't put str@nge |letters 0r characters into your emails.

  6. If you're using HTML emails, include a text part in the email as well, for recipients (and anti-spam checkers), and keep that text as close to the HTML copy as possible. The closer they're related, the less likely your email will be seen as spam.

  7. Avoid useless or needless encoding. Don't use base-64 encoded text unless you need to.

  8. Do not use invisible text within those emails. Make sure your text colours and sizes are distinct enough and large enough to read. Invisible text is often identified as a sign of spam.

  9. Always use well-constructed technically correct emails which can be identified as not-spam. Emails with invalid or missing message-ids, invalid or missing date headers, subject or other headers with unicode, etc., are frequently regarded as junk.

  10. Use a well performing, well administered and trusted SMTP server. Most undeliverable mails come from poor SMTP services, which often lead to being blacklisted: make sure your SMTP service’s staff is ready to help if you are blacklisted by mistake.

Finally you should always test a big promo email:

Test your email with SpamAssassin. Send your draft using an ISP email system with SpamAssassin running, and see how it scores. If your email hits a number of high-scoring filter rules, then you can determine why and reduce your email's score.

Run your email campaign through a free spam filter. Try Content Checker at:

And most definitely do a dry run before sending your message to your entire list. Establish accounts at major ISPs (Yahoo, Hotmail, GMail) and send test messages to each to review formatting and if it got flagged as Junk.

Some other things you can do:

  • Do a reputation audit on a regular basis to see how your emails are viewed by the monitoring services. We do this a few times a year. This is done by our email service provider, but you can try Barracuda Networks for a regulatory compliance audit, or SenderBase for a reputation lookup.
  • Try an email quality check service such as Litmus - they have testing services to enable you to see, ahead of sending, how well your email will fare against various spam filters.
  • Register your domain with the Network Abuse Clearinghouse. 
  • Watch your wording - there is a list of words that Microsoft Outlook considers particularly spam, especially when used in your Subject line


About the Author

Tony Tullio

Tony Tullio is a veteran in the interactive business and Director/Founder at Inorbital and always looking for great web apps and useful websites. Let us know what you think about this topic by commenting or rating or connect with him via Twitter and LinkedIn