8 Little Known Ways to Avoid The Email Spam Filter

by Sofia Woods

Last updated on July 10th, 2017

You can’t afford to spend time, money and energy creating email campaigns only to have them land in the spam filter.

The list of criteria for what constitutes spam is growing and more savvy software is being developed to protect people from unsolicited emails.

Make no mistake, spamming is wrong, but it doesn’t take a spammer to get caught in the spam filter. With all this robust cyber security, how do we make sure our email campaigns get to their desired destination?

Before we start, there are common mistakes that will land you in the spam filter, these still apply so if you’re new to email marketing then make yourself familiar with these common things to avoid.

Common Spam Avoidance Techniques

Choose body content and subject lines carefully

Firstly make sure you have a subject line and avoid spammy language like ‘buy now’ ‘click here’ ‘last chance to win…’ ‘why pay more’. Don’t use capitals, urgent phrases and excessive punctuation!!!!!!!!

Words like ‘viagra’ or ‘cialis’ appearing in an email are nearly always quarantined.

But they aren’t the only targets.  Using words like ‘free’, ‘cash’ or even just including dollar signs ($) in your email can trigger a spam filter particularly if they are found in the email subject line.

Get Permission

Sounds simple I know, but often the goal of trying to gain email addresses outweigh the priority to get permission.

Ensure you have explicit permission to email the registered address for the specific purpose you are intending to use it for. For example, you may have collected email addresses over time through your business for general correspondence or client contact, but this doesn’t mean these people automatically want you to start sending them coupons and specials.

Seek explicit consent so that your subscriber doesn’t mark you for spam, or even worse, report you for abuse.

Use A Double Opt In

The best way to get permission from a subscriber is to use a double opt in method.

How it works:

  • the user puts their email into an online form (First Opt In)
  • they receive a confirmation link
  • they confirm by clicking the link and then are added to the list (Second Opt In)
  • if they don’t click, then they’re not added to the list

8 Lesser Know Spam Avoidance Techniques

Now, on to some more advanced concepts in avoiding the spam box.

Use Tools

Make sure you test your email campaign before you send it. This can save you time and disappointment. Use a free online spam testing tool like Contactology or Mailing Check.

If you are using an email campaign program such as Constant Contact, Mailchimp or Mad Mimi, use their internal Spam grading tools to see how likely it is that your email will trigger spam alerts.

Use a normal font size

Fonts that are too big or too small can trigger a Spam filter.   The reason is that many Spammers either try to hide text in an email with tiny font sizes or they use huge font sizes to make an offer.  Use a standard font size  to avoid Spam filters.

Email early

If you’re collecting email addresses for your subscriber list, don’t wait until you have 1000 subscribers before you send your first campaign. Suddenly sending to large quantities of addresses will trigger spam filters. Start sending to a small group first while you are building your list.

Watch your text to image ratio

Spammers often use images to communicate their offer because Spam filters can’t read what is in the image.  Spam filters look skeptically upon emails that contain very little text but a large image.

Watch your link to text ratio

Spammers often send emails with little or no text and a link or numerous links.  When marketing with email, links are often a critical part of the email.  We usually need to place a link to the offer or to the content we are sharing with the email list.  However, be sure to include ample HTML text when including links or risk being marked as Spam.

Be careful who you link to

Just as it is important not to link to spammers on your website, it’s doubly important not to do so in an email.  Linking to a known spammer is a surefire way to get a bad reputation.

Use clean code and proofread your text

Spam filters are keen to some of the more common spam formatting like red text in the body of the email or excessive use of underlining and bolding.

But they are also looking for anything out of the ordinary.  Things like blank lines, words with gaps (spaces) in them and excessive use of the same words can add to your Spam score.

Timing is important

This issue is less related to a Spam filter and more related to subscribers that might mark you as Spam in their email program.

Develop a regular email pattern and stick to it.

If you email too often you run the risk of your subscriber marking you as junk for being annoying. Conversely if you don’t email often enough, users will forget they signed up to your list and will unsubscribe or flag the email as spam.

Avoid Spamming to Avoid Email Firewalls

Because spam is increasing at an exponential rate many email service providers (ESP’s) now have email firewalls.

They are being implemented globally throughout large businesses, ISP’s, governments and corporations. The important thing to note here is that these email firewalls communicate with one another, sharing information about who is a spammer, what spam is and who to block.

The moral of the story is that if you get enough complaints against you, email firewalls will communicate globally about your status notifying everyone that you are spammer. Obviously you can see the disadvantage to this, so keeping out of spam filters is even more important than ever.

Here are some of the widely used email gateway and firewall services:

  • Cloudmark
  • Barracuda Networks
  • Postini
  • IronPort
  • Brightmail
  • MessageLabs

Spam is a serious issue so make sure all the work you’ve put into email marketing isn’t hindered by ending up in a spam filter.

This can lead to future issues such as abuse reports and having your details shared amongst global email gatekeeper and firewalls. By understanding how spam is blocked you can ensure that you’re delivering your content in a legitimate way.



Get updates on new articles, webinars and other opportunities:

Sofia Woods

Sofia Woods is a freelance web designer specialising in WordPress web design and training, social media strategies, blogging and copywriting. She thrives on the ever changing digital world and helping people understand how to better utilise online technologies. Check out her website or connect with her on Facebook or Twitter.


Comment Policy

Please join the conversation! We like long and thoughtful communication.
Abrupt comments and gibberish will not be approved. Please, only use your real name, not your business name or keywords. We rarely allow links in your comment.
Finally, please use your favorite personal social media profile for the website field.


Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  1. Chelsea says:
    September 3, 2015 at 5:31 am

    Hi. Hopefully this page is still active and I can get a reply….
    Just a question.

    I work for a company called Yorkshire Party Bus. We ask that when people enquire about our buses, they use the enquiry form on the website. Most of these emails land in the Inbox Folder on our Hotmail account.

    However, we’ve recently been having loads of trouble with some (about a quarter out of all the enquiries we get) landing in the junk folder.

    The recipients email addresses are all normal (ie, @hotmail.co.uk, or @live.com, or @aol.com etc…..). Some of these land in inbox, and some in spam.

    There’s no wording that would give it a reason to land in spam. The enquiry forms are all the same, with multiple choice questions, so I can’t figure out why it’s only doing it to some and not to others. The font sizes are exactly the same, there’s no images, or indecent words.

    Also, we have marked “safe” all emails with endings on their email that we are familiar with, (@hotmail.com etc….), but some still continue to end up in the junk with these email addresses!

    Any suggestions please? It’s quite important to us as we don’t want to miss any enquiries. It makes us look unprofessional and we could be missing out on bookings.

    Any help would be great.

    Many thanks,

  2. Joan Stewart says:
    May 13, 2015 at 11:50 am

    Questoin: I just started using LeadPages. The words “Lead Pages” or any link with Lead Pages within it is caught by both my outbound and inbound spam program, Red Condor. Lead Pages refused to tell me their ISP number which is needed to unblock them. What can I do other than having the pages hosted on my site which, at the moment, I can’t do. I will eventually, however.

  3. adam says:
    December 20, 2013 at 3:35 am

    A Good spam filter we use to prevent spam is MXGuarddog

  4. Amir @ Blue Mile Media says:
    July 11, 2012 at 10:27 pm

    Nice article. I sometimes like to followup direct mail or phone calls with an e-mail to prospective clients and it’s hard when it goes straight to spam. From my experience, sending out the e-mails from a custom domain name makes it a lot easier to be triggered spam compared to sending from gmail, yahoo, hotmail, etc.

    I also have a good amount of links in my signature so when I send out e-mails to someone for the first time, I keep the signature with just name, company, and phone number. Hopefully it helps, but I can’t know for certain.


    • Sofia Woods says:
      July 12, 2012 at 7:49 pm

      Thanks Amir, yes following up with clients to ensure they received the mail is one way to check the you stayed out of the spam box. Spam filters get suspicious about emails that don’t have signatures so it’s a good idea to use a professional one for your business correspondence. It’s important to make sure any links in signatures are legitimate.

Show Me My Heatmap

literally addicted to the stuff I'm seeing in @CrazyEgg. Such a fantastic piece of software! #Marketing #Content #Digital

Chris Vella-Bone


What makes people leave your website?