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Email Deliverability and How To Avoid Spam Folders

by Francis Rodino

July 5, 2024

Why are my emails going to SPAM?

What is “Email Deliverability” and why is it important?

Deliverability is a measure of how many of your emails are going to Subscribers’ inboxes vs their spam folders. After putting so much work into your email marketing, you want to be sure that your messages are actually being seen by your Subscribers! This is why deliverability is crucial. 

📩 How is deliverability determined?

There are a lot of factors that influence inbox placement. In general, mailbox providers are trying to determine three things:

  1. Is the message safe?
  2. Is the message wanted by most Subscribers?
  3. Is the message wanted by this particular Subscriber?

If the answer to all three questions is yes, the message belongs in the inbox. If any of the answers above are no, this message belongs in the spam folder. To make this decision, mailbox providers typically turn to the sender reputation they have calculated for you. 

👌 Sender Reputation

Mailbox providers, such as Gmail, Microsoft, Yahoo, Outlook, etc., create a reputation score for your sending domain. You can think of this like a credit score, but unfortunately there’s no one source of truth that can indicate exactly what your score is and why. Mailbox providers keep your score, and the algorithms used to determine it, private. However, the most important determining factor is the way that Subscribers engage (or don’t engage) with your message.

💬 Subscriber Engagement

The best way for mailbox providers to determine where your mail belongs is by seeing how your Subscribers interact with it. There are actions your Subscribers can take that will raise your sender reputation, and actions that will lower your sender reputation. 

Here are some recommendations for promoting positive engagement:

👨🏻‍⚕️ List Health

  • Only import Subscribers who have given you direct permission to receive email marketing. Quality is much more important than quantity when it comes to email marketing. You don’t want anyone on your list who doesn’t want to be there. For the best deliverability, be sure everyone on your list knew exactly what they were signing up for.
  • Secure your Forms with a double opt-in and/or ReCaptcha. If your Form isn’t secure, there’s a good chance you’ll start to see bots abusing it. We talk more about why this is harmful to your deliverability here.
  • Prune your list regularly. Be sure you don’t let Cold Subscribers pile up. If you don’t clean your list regularly, the unengaged Subscribers will start to become the majority. When this happens, your sender reputation drops and more messages start to be filtered to spam.


An important component to your sender reputation is consistency. If there is any sudden change to the way you send messages, mailbox providers will see your messages as risky and potentially place it in the spam folder. Here are some characteristics you’ll want to keep consistent:

  • Sending Domain: It’s perfectly fine to send from multiple domains, but be sure the domain you’re sending from is the domain that Subscribers will recognise. Avoid sending from a brand new domain or a domain that has not sent any mail in a long time (over 6 months). 
  • Volume: Be sure to send to a consistent number of Subscribers each week. It’s normal for your list to shrink and grow, but try not to have any major volume swings. (You don’t want to go jump from 5,000 Subscribers to 20,000 Subscribers overnight!) If you need to introduce a large number of new Subscribers, be sure to start sending to them in small batches so you don’t alarm mailbox providers.
  • Frequency: Send at least once per month to keep your sender reputation established. If mailbox providers don’t see enough mail from you, they won’t be able to maintain a reputation for you and you’ll be starting from scratch on your next send. Also, be sure not to send too frequently to Subscribers — it could cause them to mark your messages as spam! We recommend asking your Subscribers ahead of time how often they’d like to hear from you and give them the ability to modify their preferences in each email.

Why are my emails going to SPAM?

There are many reasons that mailbox providers could flag your email as spam. Here are the most common reasons we see and how to fix them!

Sending From a Public Domain

If you are sending messages from a free domain like gmail.com, yahoo.com, etc., your messages will likely go to the spam folder. You’ll want to be sure to send mail from a domain that you own and that matches your branding.


If the domain you use to send mail has a DMARC policy but you haven’t verified the domain in with your SMTP provider, your messages will likely go to spam. Check with your SMTP provider for instructions on how to ensure your HighLevel messages pass DMARC.

🤝 List Health & List Collection

If all of the technical pieces above are covered, list health and list collection are the next most important factors to determine deliverability. Be sure that:

  • Everyone on your list gave direct consent to receive email marketing from you
  • Your cold subscribers are cleaned from your list regularly
  • Your forms are secured with double opt-in

🔄 Sending Internal Mail

Are you sending messages to the same domain that the message is coming from? For example, sending from info@exampledomain.com to suan@exampledomain.com. If so, it’s common for these internal messages to go to spam. This is because your mailbox sees that it’s receiving a message from itself, but it knows that it didn’t send the message (Lead Hero did). This makes your mailbox think it’s being spoofed, and it sends the message to spam.

If you’re just sending internal mail to test your messages, we recommend using a free email like gmail.com. If you need to send mail internally outside of testing, you’ll want to have the person who manages mail for your domain whitelist the IP address of your SMTP provider.

😍 Content That Avoids Spam Filters

While content matters much less than it used to when it comes to inbox placement, it still has the potential to influence your deliverability – especially if your sender reputation isn’t well established. 

If mailbox providers haven’t seen consistency from you like we covered above, they might not have enough information to decide whether your message is safe and wanted. This means they might need to rely on your content as another data point to make this decision.

On the flip side, if mailbox providers have seen enough consistent volume from you that they have confidence in the way you’ve been scored, they’re more likely to totally ignore your content. Here are some things to keep in mind:

  • Avoid Link Shorteners: Use clear, descriptive links instead of shortened URLs.
  • Skip Spammy Language: Write in a conversational tone and avoid excessive sales pressure.
  • Balance Text and Images: Include enough text for your message to be clear even if images don’t load.
  • Avoid Gimmicks: Don’t use misleading subject lines or other tricks to boost engagement.
  • Encourage Authentic Engagement: Invite subscribers to reply or interact with your emails in a genuine way.


By following these tips, you can improve your email deliverability and ensure your messages reach the intended inboxes.

At Lead Hero, we can help you improve youe email deliverability. Our system is equiped with automated email verification which prevents sending emails to bounced addresses. We can also set you up with a dedicated subdomain for your emails and make sure your DMARC and other records are set up in the best way possible. If you’d like to find out more about how we can help with your email deliverability, contact us today and schedule a demo call.

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About the author 

Francis Rodino

Francis has spent over two decades launching global digital marketing campaigns and delivering ROI for some of the world's best-known brands. From the BBC to Fifa, Playstation and Virgin, in 2018 Francis set out to make a bigger impact helping established small businesses and entrepreneurs harness marketing technology and cutting-edge digital strategies to increase sales, gain greater control and free up their time grow a business that runs itself.