8 Email Deliverbility Tips To Break Through Spam Filters

Ensuring requested opt-in email is delivered to subscriber inboxes is an increasingly difficult battle in the age of spam filtering. Open and click thru response rates can be dramatically affected by as much as 20-30% due to incorrect spam filter classification.


Confirming that the people who ask for your information have actually requested to be on your list is the number one step in the battle for deliverability. You should be using a process called confirmed opt-in or verified opt-in to send a unique link to the attempted subscriber when they request information. Before adding the person to your list they must click that unique link verifying that they are indeed the same person that owns the email address and requested to subscribe.

Subscriber Addresses

EmailWhen requesting website visitors to opt-in ask for their “real” or “primary” email address instead of a free email address like Yahoo or Hotmail. Free emails tend to be throw away accounts and typically have a shorter lifetime than a primary ISP address.

List Maintenance

Always promptly remove undeliverable addresses that bounce when sending email to them. An address that bounces with a permanent error 2-3 times in a 30 day period should be removed from the list. ISP’s track what percentage of your newsletters bounce and will block them if you attempt to continually deliver messages to closed subscriber mailboxes.

Message Format

Usage of HTML messages to allow for text formatting, multiple columns, images, and brand recognition is growing in popularity and is widely supported by most email client software. Most spam is also HTML formatted and thus differentiating between requested email and spam HTML messages can be difficult. A 2004 study by AWeber shows that plain text messages are undeliverable 1.15% of the time and HTML only messages were undeliverable 2.3%. If sending HTML it is important to always send a plain text alternative message, also called text/HTML multi-part mime format.


Many ISP’s filter based on the content that appears within the message text.

  • Website URL:
    Research potential newsletter advertisers before allowing them to place ads in your newsletter issues. If they have used their website URL to send spam, just having their URL appear in your newsletter could cause the entire message to be filtered.
  • Words/phrases:
    Choose your language carefully when crafting messages. Avoid hot button topics often found in spam such as medication, mortgages, making money, and pornography. If you do need to use words that might be filtered, don’t attempt to obfuscate words with extra characters or odd spelling, you’ll just make your messages appear more spam like.
  • Images:
    Avoid creating messages that are entirely images. Use images sparingly, if at all. Commonly used open rate tracking technology uses images to calculate opens. You may choose to disable open rate tracking to avoid being filtered based on image content.
  • Attachments:
    With viruses running rampant and spreading thru the usage of malicious email attachments many users are wary of attached documents. It’s often better to link to files via a website URL to reduce recipient fear of attachments and reduce the overall message size.

CAN-SPAM Compliance

The January 2004 Federal CAN-SPAM law introduced a number of rules regarding the delivery of email. It’s important you have your legal counsel review your practices and ensure you are in compliance. The two most important rules include having a valid postal mail address listed in all commercial messages and a working unsubscribe link that is promptly honored to remove the subscriber from future messages.

Reputation services are often used by large ISP’s as a way to vet email senders regarding their email practices and policies. Businesses listed with these services are then given less stringent filtering or no filtering at all. Several reputation services are:

Relationships & Whitelisting

Contact with major ISP’s and email providers is essential in letting them know about your requested subscriber email. Many large providers such as AOL and Yahoo have specific whitelisting programs and postmaster website areas to ensure your email is delivered as long as you meet their policies and procedures in handling your opt-in list.

Email deliverability is about ensuring requested opt-in email is delivered to the intended recipient. While no single tip will enable you to get 100% of your email delivered each one utilized as a group can go a long way to reaching that goal.

About the author: Tom Kulzer is the CEO of Aweber. Take the Aweber $1 Test Drive today.

92 thoughts on “8 Email Deliverbility Tips To Break Through Spam Filters”

  1. Awesome tips, especially for someone getting into email marketing.


    1. You can expect such kind of tips from Tom only.

      Thats why I always prefer to send emails in simple text without any formatting or similar kind of things.

      1. Salesfist says:

        plain text is the best option for an auto responder.

  2. See for some reason I always seem to forget about my list maintenance, when I do finally get around to it 30 percent is already undeliverable.

    1. Ouch… Email marketing is very powerful… Keep your lists top notch!

  3. DotComNote says:

    I use black hole techniques. I never use my email to collect free products and then getting marketed on almost daily basis for useless products. The only time I open my black hole email is when I have to confirm it. After that, I don’t open email from any Internet Marketers unless I see the same Internet Marketing program is promoted by a dozen people. And then I open one of the email to write my blog post.

    Folks, use a separate email for all those sign up to get free products. Now I am finding the the best materials are in the free products. I think the Jedi Master has told all Internet Marketers to give valuable products for free.

    1. The Jedi Master eh? Talking about black holes, how well do you know your various planets? Especially the one called Uranus……bwahahahahahahah

      Sorry friend, I couldn’t resist the joke. Things are boring this morning and some comic relief was much needed.

      1. Haha nice ones you got in a row 😀

      2. LOL…glad you couldn’t resist..it was pretty funny.

        “Avoid creating messages that are entirely images. ” that is an instant spam on my email 🙂

        1. That’s why I love Net Age comments … to the point.

  4. Benjamin says:

    Good Ideas John…. By the way I have seen that Mailman image on another site where did you get it?

    1. John Chow says:

      Google image search.

      1. And if you want to use it legally, you can obtain an image license here: http://bit.ly/bBaMNu Remember, also images you find with Google Image search are under copyright protection, SY

        1. Oh yeah forgot about licensing… Thanks for the reminder!

          1. You are welcome 😉 SY

  5. PPC Ian says:

    Wow! Very useful information. I recently started experimenting with email marketing in the last year and must say I’m breaking some of these rules. These are some really actionable tips and I very much appreciate the advice!

    1. Addy Kho says:

      But some of them really difficult to follow

      1. Which ones? They are all clear as glass and easy to implement! What are the rules you have problems to follow? SY

  6. Hey Tom,

    These are awesome tips man. “List Maintenance” is something i have to do now. 🙂 !!

    Thanks for sharing this great Post.


  7. d3so says:

    The CEO of Aweber?! Nice. Thanks for the tips. These will definitely help ensure that emails are being sent to subscribers. Though I must admit, I’ve violated Can-Spam back then which caused my mass emails to be marked as spam 😛

  8. Jay says:

    Is a service like Aweber worth it when first starting out your blog?

    1. John Chow says:

      Start your list from day 1. Not doing that was the biggest blogging mistake I made.

      1. d3so says:

        I’m making the same mistake because I’m being cheap 😛
        Is it possible to import emails from feedburner to aweber?

        1. If you want to import anything into Awever, your subscribers have to opt-in again, and that means you will most likely loose a lot of them in the process. So, it is important to decide from the beginning with which subscription service you want to go. Oh, and btw, Feedburner is for notifications when a new blog post is posted, Aweber and similar is for sending messages to an email list directly, without going through your blog. SY

          1. d3so says:

            Opting in again isn’t importing lol. I know the difference between aweber & feedburner. I was just wondering about the possibility of importing an email database into their system, that’s all.

          2. Hey d3so, I noticed you have tons of Feedburner subscribers. HINT: You’ve got an asset (money-maker) right under your feet.

            But you should (in my humble opinion) try getting everyone to subscribe to your email list.

            John just threw some wisdom for everyone:


          3. d3so says:

            fine, fine! I suppose I’ll sign up since the first month is ONLY $1 😉
            If I don’t make at least one dollar from my list within this month I’m gonna be so pissed haha.

          4. PPC Ian says:

            I’ve been using AWeber for about 9 months now and have built lists for my blog and also one of my static sites, I highly recommend it! The tools are top notch and I’m anticipating some nice profits a year from now as my lists continue to grow! It’s all about the long term with email in my opinion.

          5. Even after you have imported a list into Aweber, they will ask all people on your list to opt-in again. You can’t just add email addresses to Aweber without that happening, SY

          6. d3so says:

            I suppose that’s true cause they have to confirm the subscription to the list 😛
            Oh well, it was worth a try.

          7. It is true because they have pledged to confirm with anti-spam rules! SY

          8. d3so says:

            @Ian are you currently making profits from your lists?

      2. Addy Kho says:

        John, may you share the experience on how to use email marketing to sell? We tend to receive lots of email every day or even send out sales pitch every day via email. How do you make sure your campaign is successful and not offending people if we keep sending people email? May be you can do a blog post on that.


        1. Just subscribe to his email newsletter and you see first hand how he does it 😉 SY

      3. I’m building lists on all my sites now John, per your tip. 🙂

        1. PPC Ian says:

          Me too! John’s advice is top notch. I have lists on 2 of my sites. However, I now have about 25 left to go! 1 at a time, I keep telling myself!

          1. Jay says:

            Thanks for all of the replies and helpful insight into the matter. I’ll sign up for Aweber tonight. 🙂

  9. @Tom
    Nice tips, from somebody who is knowledgeable in this industry. Unfortunately I am getting still spam mails due to this event: http://www.aweber.com/blog/uncategorized/data-compromise.htm Whilst you have apologized to your customers, I haven’t seen an apology to all the people whose email addresses have been compromised and that are still receiving spam due to this. SY

  10. The money is in the list, and that means that managing the list is of critical importance in order to facilitate the maximum return from your email marketing efforts. If 20% – 30% of your mails get trapped in spam filters there definitely is work to be done in order to remedy this forthright!

  11. Addy Kho says:

    It is getting harder to practise email marketing as compared to olden days 🙂

  12. Hi Tom,

    Great tips for everybody. I appreciate everything that helps with building email lists and that improves relationships with those who opt in.


  13. Emily says:

    I think feedburner is OK but aWeber is much more professional.

    1. Feedburner and Aweber are two completely different things, as outlined above, SY

  14. Free Picks says:

    good tips for email marketers as well

  15. Joshua says:

    Title should read ‘Deliverability’. Should fix that up so I can tweet it with pride. 😉

  16. Hey John,

    We met briefly in August 2008 at Yaro Starak’s meetup at some Organic Cafe place in North Toronto.

    I was going to start following you on Twitter, but there was a notice saying that your account has been suspended??? Not sure if you were aware of it?

    1. Addy Kho says:

      It was reinstated as mentioned by John before I guess. Correct me if I am wrong John.

    2. John Chow says:

      I am aware of it and I’m talking to Twitter about it.

  17. Edward Nigma says:

    Why does this all mail marketing thing looks that spam to me? I am going to setup a newsletter myself, but somehow I cannot get rid of the thought that it is too close to the spam-line. B-r-r-r

    1. Email marketing is a tool, nothing else, it is the user that makes it spam or not. SY

  18. Some other good ones is to not use all capital letters and avoid the word free

  19. DC Figures says:

    Yeah, certainly avoid the word “free”.

  20. I remember the list advice from your video a few months back. I hope to sign up with Aweber soon.

  21. d3so says:

    So, I signed up for aweber, got my lists going (check it out: http://www.d3so.com), then I realize my PR dropped to ZER0, WTF?! coincidence?
    Yes, I care about my PR tyvm.
    Any ideas regarding my PR?
    Any suggestions on my list form?

    1. Addy Kho says:

      you mean after you sign up with aweber, your PR drop to 0?? It is interesting to know..

      1. d3so says:

        Yup and it sucks!
        Anyone have any idea why this happened?
        I’m just in shock right now 🙁

        1. Rofl, there was a minor PR update over the last few days, but I can reassure you it has nothing to do with signing up to Aweber. Not everything what happens at the same time is connected. Most likely is that you lost a few good backlinks from other sites and that caused your PR to drop, SY

          1. d3so says:

            I highly doubt I lost any backlinks because my blog was inactive for the past year and I recently started posting and link building.
            Damn, I think I know what happened. The increase of backlinks probably set off an alarm because I increased from 100+ backlinks to 6000+ in less than two months.

          2. Great amounts of backlinks does indeed set some alarm. But not like it used to. If it was 3-4 years ago, your site would’ve dropped from Google. But now, that kind of change would not have a negative impact on your site. It would only reduce the quality of the each link.
            I’d say, be patient. I’m sure you’ll get your PR back 🙂

          3. d3so says:

            I don’t know, if I lost PR with a blog I’ve lost it for good 🙁
            check out my blog and see if anything might of alarmed google.

  22. Nick says:

    Great post John and useful tips. The money is in the list, and is very important know some of these rules. Thanks for sharing it.

  23. Earl says:

    Hey John, great post as always. I’ve got a weird question for you. If you had $1500 burning a hole in your pocket to buy training with – that had to better you AND your productivity for your company, what would you spend it on?

    1. Addy Kho says:

      i am not John but my thought is: If it helps your company and $1500 is nothing to you but only an investment of the company, then why not

      1. Earl says:

        Actually it’s a freebie from the government. Might as well take advantage of grants when they come, and while they last.

  24. Great post John, this would be abig help for those of us involve in such activities.

  25. Mike G. says:

    Man…I’ve been getting alot of SPAM on my website and I haven’t even do any marketing on it . Anyone know a good wordpress plugin to automatically block SPAM?

    1. Jay says:

      I’d suggest using Akismet. The plugin comes bundled with WordPress by default. It’ll be able to stop spam from being displayed.

      1. d3so says:

        Askimet isn’t perfect though. I get legit comments being marked as spam. 😛

        1. I recommend using a captcha, that keeps the robots under control, so you only have to cope with the human spammers, SY

          1. d3so says:

            That’s true, captcha can help but I think it makes it more of a hassle for the user to leave a comment.

          2. I concur it creates a hassle for the user on commenting. And the human spammers are still an important issue even with the captcha!

          3. d3so says:

            That’s true, sometimes I have a hard time tryig to figure out spam comments from legit ones 😛

  26. Thanks for the tips John, will implement that into my emails.

  27. Thank you for the tip about list maintenance, Tom. I’ve always thought that AWeber will take care of bounced email and remove the email address from my list automatically. Must be more active about list maintenance from now on.

  28. Justin Dupre says:

    Very helpful post! I like many of your tips. Thanks for sharing.

  29. d3so says:

    I joined aweber today and created my first list!
    Check it out and SUBSCRIBE! http://www.d3so.com
    what do you about my form? Should I change it?

    1. I would change the RSS feed icon for something else in your sign up field. It is not really clear that people sign up to an email list and not a RSS Feed, just my two cents, SY

      1. d3so says:

        I thought so, thanks for your input!

        1. You are welcome! SY

  30. Lovely tips John. Thanks!

  31. Awesome tips. I find Aweber’s spam rating to be really good for me. I make sure my messages are always 0.0 and I usually get very good delivery.

  32. Wynne says:

    Great tips John, I especially like the one about cleaning up your list and looking for high bounce rates and taking them off your list. This is so important for cutting down the spam rating of your list.

  33. If this works will help my traffic numbers dramatically.

    1. d3so says:

      Not only traffic but you can also sell products to your list!

  34. Some nice tips there. The spam filters are necessary, but a pain when my good messages get caught in there!

    1. d3so says:

      Aweber even has a feature that scans your message before it’s sent and gives it a spam rating. If it’s below a certain number it can be sent.

  35. Other than aweber, what other newsletter services are out there that people use?

  36. Jennifer says:

    Thanks for a great article especially the links to the can spam laws.


  37. Yeah thank you for sharing this, I will need this very soon!

  38. Thanks for the email tips! Can’t wait to try them!

  39. Thanks John for the info. I think I will try text emails and see if that doesn’t improve my click through rate.

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