The SPAM Formula – How to Beat the Filters at Their Own Game

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Did you know that 15% of all emails sent never make it to the inbox? We’re out to change that at ConvertKit and we’re focused on high deliverability. It’s what’s best for us, for your readers, and for YOU.

One of the biggest questions we’re saddled with on a regular basis is something along the lines of:

“Hey! I love you guys (sending you roses right now, btw), but how do I get my emails to stay out of the SPAM filter?”

Something like that.

Well, aside from driving to each of your subscriber’s houses and personally delivering the (hand-written) letter for you, we have a few suggestions to help ensure your emails end up in the intended inbox.


test your inbox - ConvertKit


First off, let’s talk about what we’re already doing for you:

  • Built-in CAN-SPAM compliant address
  • Automated/immediate unsubscribe handling
  • Feedback loop subscription & complaint handling

Before we dive into the next part, there’s some good news/bad news: These are all actions YOU must take. We do our part for you – a good 30% of the effort is on our end – but the majority of actions that keep your emails away from SPAM filters in on your end. So… bad news: it’s work you have to do. Good news: it’s all really easy!

Ready? Let’s unpack it.

So here’s the two secrets to passing SPAM filters with flying colors:

  1. Create good content
  2. Maintain a clean, permission-based email list

That’s it! Easy, right? Maybe not quite SO easy.

Think of email clients like a well-trained family dog. When that dog sees a friend, neighbor, or someone they recognize and trust, they wag their tail and get out of the way so that friend can come in and play with them.

But if the same dog sees someone they don’t recognize, their fur on their back stands up and the tail stays still. If that unrecognizable person is also wearing a hat and sunglasses and a big poofy coat that covers them up, that family pooch begins to growl. By the time this stranger gets to the front door, Fido is barking his head off making it clear that this visitor is not welcome.

Just like Fido can be trained to recognize friends and family (who just happen to be wearing hats or sunglasses from time to time), email clients can be taught to recognize your emails with a little love and attention.

How to create good content to beat Spam filters

According to email marketing expert (and my new favorite marketer ever) Jessica Best, here’s what good content looks like:

  • Balance of images and text (or 500+ characters of text)
  • Watch your language
  • Go easy on symbols and using ALL CAPS
  • Use clean, email-friendly HTML code and design

Does that last one feel familiar? We’ve talked before on this blog about why email templates aren’t always your friend. Use them with caution if you’re using them at all.

Okay, so you’ve checked off all the boxes above, but you want to be absolutely sure your emails look the way you want them to in every inbox possible. Do you need to get yourself a GMail, Outlook, Yahoo, AOL (yep, it’s still a thing), Hotmail, Apple Mail, an iPhone, Android phone, iPad, Kindle, Amazon Fire, and 25 other email inbox setups and devices to test it?

Sure, if you want to make yourself crazy.

If, on the other hand, you’re into keeping things simple on the testing side but you still really want your templated emails, you can try Litmus. With Litmus you can “preview your broadcasts across 40+ real email clients and devices in minutes.” They make it simple to see how your emails will look all across the board before you ever hit send.


try litmus


Of course, if you stick with text-based emails, your deliverability gets bonus points for not scaring any email client watch dogs.

Now about that list…

How to maintain a clean, permission-based email list

Having a clean, permission-based list means:

  • NO purchased lists
  • NO subscribing people without their explicit permission
  • NO sharing lists with other businesses without giving the subscriber the option to opt out of that sharing

Basically, think about how you want to be treated with your inbox and do that. In the words of mothers around the globe: if it sounds like a bad idea, it probably is.

Don’t make your mom say “I told you so”. Keep it squeaky clean.

Are we dating or are we breaking up?

Think about your open rates. So you’re feeling pretty good about your 26% or 37% or 42% open rate. Maybe you’ve even seen some 68% or 83% open rates. Good for you! So then you’re thinking that the remaining percentage just didn’t open the email that time, right? Wrong. Up to 40% of your list never actually opens your emails.

Now, before you run off and call me Debby Downer (because I kinda am here, TBH), this is actually NORMAL and a good thing to know. I learned early on from School House Rocks that Knowledge is Power! so now it’s time to do something with this info.

One of the leading data collection sites for marketers, Marketing Sherpa, had this to say about those sad stats:

Sometimes people fall out of love … with your newsletters and email marketing. Or change jobs. Or email providers. There are a million reasons why they stop reading and engaging with your emails.

This is why email marketers need to run win-back campaigns. That is, reaching out to inactive subscribers and compelling or convincing them to re-engage with your email sends.

If they don’t re-engage, it’s time for a list cleansing — no longer sending emails to this group.

Enter the cold subscriber filter.


cold subscriber filter in ConvertKit


No matter how engaging your content is, some subscribers will always lose interest over time. That’s fine. It’s not about having the biggest list, but instead the most engaged list. So you can prune cold subscribers from your list after they haven’t engaged for a while.

At ConvertKit, we define cold subscribers as anyone who hasn’t opened or clicked an email in the last 90 days and has been subscribed for at least 30 days.

But don’t just drop ‘em off your list unannounced! Re-engage them before kicking them out the door. You’ve probably seen it done by e-commerce sites but have you considered re-engagement campaigns for your own brand? Here’s three ways Jessica Best points out that give your cold subscribers one last chance to interact with you:

We Miss You! Come back and receive X

Telling your readers how much you care about them pays off. Send a quick note telling them that you miss them and maybe even make an offer to keep them engaged. You could give them a free download or an invite to an exclusive webinar – something valuable that your ideal subscriber would want. If they don’t take action, you can feel good about letting them go.

Confirm Now to stay subscribed or miss out on X

Give them the exact steps you want them to take. By saying “Confirm Now” (even if they technically already confirmed when they subscribed) puts the action in the subject line and gets them to notice. A little reminder of all the great content they’ll miss out on if they don’t confirm

Sorry To See You Go Re-Subscribe at any time

This one employs a bit of a scare tactic, but it works. “Wait, I didn’t unsubscribe!” they’ll say, and quickly click inside to stay up to date.

Of course, with all of these options you do want to have that link trigger inside the email itself that, when clicked, indicates they want to stick around.

But wait, there’s more!

So you have useful relevant content, you’re getting your subscribers to explicitly opt in, and your email marketing system is doing their part… you’re all set, right?

Not quite. There’s three more things to think about:


How often are you emailing your list and are they expecting emails from you at that rate? If you either:

  1. Email every single day without being clear about that up front
  2. Drop off the face of the earth and then randomly start emailing again months later

Both of those can trigger spam filters and they increase the chance your emails will be marked as spam by the reader.

We highly recommend using email sequences for this very reason. When your new subscriber is opting into a sequence of emails they get used to hearing from you on a regular basis. Then when you send your standard broadcast style emails, they know and trust you in their inbox and are happy to hear from you.


Take a look at that subject line before you hit send. Is it full of special characters, written in all caps, or even containing trigger words? Clean up your subject line to keep the spam police from locking you up.


In a world of massive (and I mean MASSIVE) communication happening every day, specificity is key. By using features like link triggers (found in ConvertKit, btw), you can send targeted emails only to people who have expressed an interest in that particular topic. In our own testing with link triggers, we’ve seen upwards of 70-90% open rates and little to no unsubscribes.

Targeting specific sets of your audience with specific content chosen just for them makes your subscribers feel like you’re really listening and it keeps you off the spam lists – a real win/win.

We're all human

When all is said and done, staying out of the SPAM box and heading straight to the inbox requires you to do just one thing: be a human. Act like a human talking to another human when you send emails. Treat their inbox the way you want yours to be treated. And, above all, listen to your momma. Because if it sounds like a bad idea, it probably is.

Val Geisler

Val is a yogi, mom, military wife, and avid podcast fan. She is ridiculously obsessed with sharing and creating content that actually makes a difference in the world, connecting with her fellow bloggers, and doing more with less effort. Val is based on Columbus, Ohio (O-H!) and can often be found oversharing on Instagram at @lovevalgeisler.

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