Do you have low email deliverability rates? This could mean that your emails are getting flagged by spam filters or blocked by ISPs.

If you are a marketing or transactional email sender, getting an email to your subscriber’s inbox is an essential part of what you do. Marketing newsletters, promotional offers, email receipts, order confirmations, password resets are a few types of email that are a highly valuable part of everyday business. Unfortunately, it’s all too common that we see legitimate email senders asking us why their email is going to the spam folder instead of the inbox. So how can you avoid having your emails go to the spam or junk folder?

The truth is, there is a lot that goes into successfully delivering marketing and transactional email to the inbox. From staying on top of best practices to managing servers- email sending can get very complicated, very fast.

The inbox placement rate of email is about 85%. But, it still means that about one out of every five emails sent either gets blocked entirely or gets filtered as spam.

To tackle this, you first need to know why it happens, so let’s talk about it.

Why Emails Go to Spam Instead of Inbox

One of the primary reasons that your emails end up in spam folder is that spam filtering has become more rigorous. The ISPs are simply cracking down on spam. Although, these filters aren’t 100% accurate, as a result sometimes totally legit emails too end up in the spam box.

But here’s the tricky part;

The engagement with your subscriber plays an instrumental role in email deliverability. That’s because ISPs look at your recipient behavior and engagement levels when deciding which emails make it to the inbox.

But not anymore! We’ll explain the top 12 factors in detail so you can avoid getting flagged and stop your emails from going to spam.

Top 12 Reasons Why Emails Go to Spam

There are many factors that go into whether or not your emails get delivered to the inbox of your subscriber. Let’s dive into the following top 12 reasons why your emails aren’t getting past the spam filters.

You Have Poor Engagement Rates

Top ISPs have clearly stated that they look at how many are deleted without being opened and how many emails are opened as a factor in their spam filtering decisions.

So if you have poor read rates or open rates, your emails are at much higher risk of being flagged as spam. While the average read rate across industries was 24% in 2018.

So, to increase your open rates, perfect your subject lines, keep your list fresh, send your emails at the right time, and segment your list.

Meanwhile, improving your read rates means writing better email copy.

You Didn’t Get Permission to Email

The first rule of email marketing is to acquire permission from your subscribers to email them.

To acquire permission, you’ll need an opt-in form on your website or landing pages that make it clear that your visitors are subscribing to your email list.

Don’t manually add emails to your subscriber list that you got off of business cards collected at some event. Since sending them emails violate the CAN-SPAM Act because they did not give you permission to receive emails from you.

On the other hand, you should send those leads email. You can follow-up with a drip campaign, auto-responder series or personal emails designed just for those leads and also offer them the chance to subscribe to your newsletter.

Your Subscribers Don’t Remember You

The second most common reason that emails don’t reach their intended inbox is spam complaints. The overall average spam complaint rate in 2018 was 0.39%, around double mailbox providers’ recommended 0.2 percent.

Whether the email is actually spam or not, every time a subscriber reports an email as spam, the spam complaint gets recorded by the mailbox provider. And once these spam complaints reach a certain threshold, all future email campaign gets sent directly to the spam folder instead of the inbox.

Are you wondering that why would a subscriber mark your email as spam when it clearly isn’t? Well, the most common reason is that they just don’t remember you. Even though they gave you permission to email them, but they don’t remember doing it, so they think you are sending them spam email.

To avoid this situation, ensure that the branding in your emails is highly memorable, and also matches the branding on your website. This includes any logo, images, colors, voice, typography, etc. Also, ensure that the “from” field is from a name they will easily recognize.

If your subscribers don’t instantly remember you, you could very easily get spam complaints, so always keep that in mind.

Meanwhile, ensure to include an easily accessible “unsubscribe” link so that they can easily unsubscribe from your list if they no longer want your emails.

Your IP Address Was Used for Spam

Your emails could easily get flagged as spam if your IP address was used by someone else for spam, even if you never send spam yourself.

Example, if you send your emails campaigns through email service provider (ESP), your emails are delivered through their servers. Let’s say you are sending your email campaigns using shared IP, so if even just one other customer that is sharing this IP sends spam, it could affect your email deliverability as well.

Note, however, that every ESP we recommend is quite vigilant about keeping their sending reputation intact, and they also have very strict regulations and procedures in place to avoid this kind of thing.

Your “From” Information is Inaccurate

It’s strictly against the CAN-SPAM Act to mislead any person with your “to”, “from”, “reply-to”, and routing information.

Example, if you made your email look like it was from Donald Trump that would be totally illegal. Yes, an extreme example, but you get the point, right?

So, as a best practice, ensure you include a name in the “from” field that your subscribers are more likely to remember and avoid changing it too often. The “from” field could be the name of an individual, your company, or a combination of your name and your company. Whichever you choose, go for consistency and memorability.

You Have Low Mailbox Usage

The third most common reason for poor inbox placement is low mailbox usage.

ISPs, in their spam filtering algorithm, look at the ratio of active to inactive accounts on your subscriber list. An inactive email account is an account that is very rarely ever used or that hasn’t been used for a long time.

It’s a red flag to spam filters if you are sending emails to a large number of addresses that appear to be nearing abandonment.

To avoid this, periodically clean up your list of any subscribers who haven’t engaged with your campaigns in a while.

Meanwhile, your ESP may also include a feature to automatically purge any emails from your list that look like abandoned addresses.

You Didn’t Include Your Physical Address

Legally, you must include your physical address. This can be your current street address, a post office box that has been registered with the U.S. Postal Service, or a private mailbox that is registered with a commercial mail receiving agency established under the Postal Service regulations.

If you are the owner of small business and you work out of your home, you should definitely get a P.O. Box for business purposes so you don’t have to broadcast your home address in your emails.

Your Subject Line is Misleading

Like the CAN-SPAM Act states, it is against the law to intentionally mislead anyone with your email subject line, in order to entice them into opening the email.

According to a survey by Fluent and Litmus, more than 50% of the participants said that they have felt tricked, cheated, or deceived into opening a marketing email by that email’s subject line.

Following are some examples of misleading subject lines:

  • RE: CURRENTLY IN OFFICE is twice sneaky because it can be easily mistaken for a reply to your email or a work-related email.
  • Thanks for your order! It’s very poor form to use a transactional subject line if the email isn’t really transactional.
  • Did I leave my keys at your place? This type of subject line can be used as a trick to make it look like they know you.
  • Urgent – Update your information. If something says “urgent,” it had better be urgent.

Are you wondering why would anyone ever do anything like this? These are some super shady tricks.

You’re absolutely right. But there are some grey areas as well that you should avoid, too.

Example, consider that you’ve just written a blog titled ” 5 tips for increasing LinkedIn engagement” and you want to share it with your email subscribers. And to get them to open your email, you considered being sly with a subject line like “5 reasons you should never post to LinkedIn”. But when they open your email thinking something just changed drastically within the LinkedIn marketing and you’re like, “Just kidding, folks. But here are 5 tips I actually wanted to share with you”.

Maybe some of your subscribers get amused by this but others not so much. The bottom line is that is it really worth taking the risk?

You Used Spam Trigger Words

Many spam filters are triggered by specific spam words in the body of the email or the email subject line.

Following are some common spam trigger words;

  • great offer
  • amazing
  • promise you
  • risk-free
  • cancel at any time
  • check or money order
  • increase sales
  • click here
  • congratulations
  • dear friend
  • this is not spam
  • for only ($)
  • free or toll-free
  • guarantee
  • winner
  • order now
  • special promotion

Your ESP may have a built-in tool that checks your email for spam trigger words before rolling out your email campaigns. Alternatively, you can also use third-party tools to see if your emails are likely to trigger spam filters.

You Didn’t Include an “Unsubscribe” Link

You just can’t build a house without any doors and you can’t send emails without an unsubscribe link within them.

Irrespective of what you think your email campaigns are, you still need to provide your subscribers an easy way out. And if you don’t, you could easily get spam compliant, imposed penalties, or the worst that your account gets suspended or blocked.

So, in the footer (bottom) of your emails, add an unsubscribe link or any other similar opt-out method.

And when any of your subscribers ask to be removed from your mailing lists, you need to process those requests within 10 business days. Also, you can’t charge them any fees to remove them or ask for any information other than their email address or make them do anything other than sending a reply email.

Example, you can’t ask your subscribers to fill out a form explaining why they want to unsubscribe before they can actually unsubscribe. On the other hand, if you do want to survey your subscribers, show them the survey just after they have successfully unsubscribed or in the unsubscribe confirmation email, but not before.

Your HTML Emails Don’t Follow Best Practices

If send text-only emails, you don’t have to worry about this. However, if you send HTML emails with a text-only version, you can easily add several branding elements that make your emails more memorable that help to improve engagement with your subscribers.

When we tested plain text email versus branded HTML emails, we found that branded HTML emails get higher engagement.

However, you need to follow the following best practices for sending branded HTML emails to avoid getting your emails marked as spam;

  • Keep your HTML code clean and as simple as possible. If you are using a template from a reputable ESP, you should be fine.
  • Optimize your emails for mobile. Ensure that your emails are readable and load quickly on mobile devices and that your links can be accessed easily with the press of a thumb.
  • Use a maximum width of 600-800 pixels. This will help them to look good in most email clients.
  • Keep your image-to-text ratio low. Images are good to add in your emails, but never send image-only emails with no text.
  • Don’t use obscure fonts. Stick with fonts that work across platforms like Arial, Georgia, Verdana, and Times New Roman.
  • Optimize your images for your email by compressing them. And avoid using super-high-resolution images or other media with very large file size.

Bad Email Design

When designing the email for your next email campaign, it’s critical to follow some of the best practices like the following;

  • If it’s a marketing email, the email must include a physical address to stay compliant with the CAN-SPAM Act
  • The email should be mobile friendly and should also be compatible with desktops
  • Avoid spam trigger words like risk-free, toll-free, special offer, dear friend, etc.
  • The email should be branded so your subscribers can recognize you easily (This includes things like logo, fonts, colors, images, and tone)
  • Your email should not be images only, maintain a good image to text ratio
  • The text in your email should be to-the-point, simple, and easily digestible for quick readers


While these tips are great for email senders trying to deliver their emails to the inbox, but there is so much more to consider. Thankfully, a good ESP can help you to ensure you have everything that you need to avoid getting your emails land in your subscriber’s spam folder. From IP warming and authentication to metric tracking- a good ESP does most of the hard work for you and also gives you access to their tools and platform that you need to effectively deliver your emails to your subscriber’s inbox.

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