What Makes an Email Spam?

What Makes an Email Spam?

The world is drowning in spam.

In 2022, an alarming 49% of global emails were flagged as spam…

And email providers like Google are hard at work blocking the 100 million spam emails that are sent every day.

But not all emails that get blocked are actually spam…

And if you own a business, your genuine emails could also be getting flagged as spam too, reducing the effectiveness of your email marketing campaigns and costing you potentially thousands of dollars in lost sales.

That’s why in this article, you’re going to discover exactly what makes an email spam so that you can ensure your emails are actually being delivered to your customers.

What Exactly Is Email Spam?

Email spam essentially means “junk mail”, and is synonymous with unsolicited bulk messages that are sent via email.

The name finds its roots in a Monty Python sketch revolving around a restaurant that serves the canned pork version of spam with every meal.

The first ever spam email was sent in 1978 by Gary Thuerk (a marketing manager at the now obsolete Digital Equipment Corp) to promote one of the company’s new products.

Fast forward to today, and a whopping 3.4 billion spam emails are being sent daily (mostly in the form of advertisements and adult content).

What Makes an Email Spam?

Spam emails are known for having various traits…

And understanding them can help you prevent your own emails from being marked as spam.

1. Spam Emails Are Unsolicited

The last thing anybody wants to read is a spam email…

Which is why most of them are sent without the recipient’s knowledge or consent.

Therefore, one way to avoid having your emails marked as spam is to ensure you are only sending to people who actually want to receive your emails and expect them (for example, those who have willingly signed up for your emails).

2. Spam Emails Use Clickbait Subject Lines

Spammers craft their email subject lines strategically to grab the recipient’s attention to make them more likely to open the email…

And these subject lines often contain deceptive or entirely false promises of monetary gains or urgent warnings.

One easy way to avoid doing this in your own email marketing is to simply ask yourself:

“Does this subject line accurately reflect the email’s content?”

If not, chances are it will be seen as clickbait and will have a higher risk of being marked as spam.

3. Spam Emails Contain Lots of Links

Another feature of spam emails is that they tend to have lots of hyperlinks…

And these links typically lead to insecure or malicious websites.

This is important to know because even if your embedded links are legitimate, spam filters are still more likely to flag your email if you include too many.

So, while it’s good to include relevant links in your email, you should make sure to keep the number you use to a minimum.

4. Lack of a Legitimate Sender Address

One big giveaway that an email is spam is that it lacks a legitimate return address.

This most often manifests as a weird-looking email address that doesn’t match the organization it claims to be from – a big red flag for spam filters.

One way to ensure your emails are seen as legitimate is to avoid using generic free email addresses such as “@gmail.com” or “@yahoo.com” and instead use a professional domain name email address that matches your brand.

Another way to signal that your email address is legitimate is to employ email authentication methods such as Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-Based Message Authentication, Reporting, and Conformance (DMARC).

This prevents spammers from spoofing your email and pretending they are you in order to get your customers’ information (which shows email spam filters that your address is credible).

Here’s a useful guide that shows you how you can authenticate your email address.

5. Spam Emails Use “Spammy” Language

Overusing typical “spammy language” is another common aspect of what makes email spam.

Email spammers often overuse capital letters, use an abundance of exclamation marks, as well as salesy wording such as “FREE”, “Buy now” or “Act now”.

Today’s spam filters are smart enough to recognize these tactics and are likely to flag emails that use them as spam.

So, when writing your emails, avoid overusing capital letters, exclamation marks, and salesy language – this will not only help avoid triggering spam filters but will also help your content resonate more with your more “savvy” readers.

6. Sent to Illegitimate Addresses

This is one thing you won’t be able to tell from looking in your inbox… but one more thing spam emails have in common is that they are often sent to illegitimate addresses.

This includes addresses that are spam traps, belong to bots, or are simply inactive or obsolete.

It’s crucial that you avoid sending emails to these illegitimate addresses because email spam filters are able to see whether your emails are being opened and engaged with by readers (and if they’re not, they’ll be more likely to be marked as spam).

One easy way to avoid sending to these emails is to use an email validation tool, which is a tool that uses preset and real-time rules to weed out the bad addresses from your list.

What’s more, if you set up an email validation API, you can filter out these illegitimate email addresses as they are entered into your email sign-up form.


Spam email is essentially unsolicited junk mail sent in bulk.

To safeguard your emails from ending up in the spam folder, ensure you:

  1. Have your recipient’s consent
  2. Avoid using clickbait subject lines
  3. Limit the number of links you use
  4. Send from a trustworthy and authenticated address
  5. Don’t use spammy language
  6. Send only to legitimate addresses

Finally, we highly recommend that you set up an email validation API on your website to ensure that only legitimate addresses subscribe to your list.

Get started today

Sign up and get 200 free credits, as well as the opportunity to test our list cleaning and API capabilities.