The definition of Spam

The question you may have been asked a lot over the past few years or you asked this question yourself:

“What is Spam?”

Simple question but a very complex answer based on a variety of dependencies and circumstances.

Me personally, I developed a very simple answer that takes the original definition from the very past as well as the development over the past years into consideration:

“Spam is unwanted email in the inbox!” – simple as that.

Please, let me explain my personal statement by show casing the development and factors that play an important role.

The formal definition of spam

Wikipedia provides the most common definition of spam, which already mirrors the development of spam over the course of more than 2 decades:

The core sentence that is still in most peoples mind is the following:

“Spammers collect email addresses from chat rooms, websites, customer lists, newsgroups, and viruses that harvest users’ address books. These collected email addresses are sometimes also sold to other spammers.”

The statement presumes that spam is only considered and combined with legally not compliant acquisition practices. Many people still think a legally valid consent avoids spam, which isn’t true.

Different understanding of spam

The email eco system includes different parties, who all have a different understanding of spam.

  • Email subscriber – extremely different due to their knowledge, experience and professional background
  • Email Marketing Brand
  • Mailbox Provider
  • Email Service Provider
  • Security Software Provider
  • Lawyer

Email subscriber

Email subscribers consider spam due to their various use cases and background. Even if they explicitly signed up for a classic newsletter or any other email type via double opt-in, their judgement about receiving the email in their inboxes may change and they start clicking on the spam button. It is a very subjective way of considering spam and the most challenging one. In a future blog post we will further deep dive into it.

Email Marketing Brand

A brand that runs email marketing considers spam from a completely different angle. First of all, spam for a brand is coming from external sources such as email fraudster or other brands or businesses who may impact their own email strategy and goals negatively.

Brands very often describe themselves as victims of spam fighting practices from Mailbox Provider or Security Vendor. I very often heard the statement: Spam is what the Mailbox Provider considers as Spam without any transparent background.

Only very few brands consider their own content, strategic approach or practices as spammy against their email subscriber.

Mailbox Provider

Mailbox Providers mainly focus on customer experience and satisfaction. They offer a service/product to their account owner and want to fulfil the expectation of their customer by providing a secure and clean email service without spam or any other security risks. This means that hard facts like authentication, behavioural schemes, content and recurring suspicious practices lead Mailbox Providers to consider certain inbound email traffic as spam. Beside their own knowledge base and research, Mailbox Provider also often use external information sources or security solutions to optimize their email service for their customers.

Mailbox Provider also consider their direct customer feedback into account, such as spam clicks or moving emails from the inbox into the spam or junk folder. To constantly learn and optimise, Mailbox Provider use hundreds of different data sources to observe and fight spam.

Even though there is exchange between Mailbox Providers about best practices, thousands of MBPs run their own mechanics and follow their own rules to fight spam.

Mailbox Provider are highly likely to consider legally valid bulk advertising from mass mailers as spam, because those emails follow suspicious practices or a huge amount of email users constantly complain about it.

Email Service Provider

The technical responsibility of an Email Service Provider is quite obvious. ESPs basically make efforts to avoid spam by providing up to date technical practices and setups for the best authentication and email standards via SMTP transmission. From an ESP perspective it needs practices against external spam factors such as domain phishing, spoofing or any other fraud.

Professional ESPs also work hard to ensure that brands use best practices to collect legally compliant email consent. Usually they provide technical tools for save email acquisition.

So basically, from an ESPs standpoint, spam is mainly defined by technical and consent related dependencies, because this is the parts they are able to influence the most.

Security Software Provider

Their job is to protect critical systems or data. They are hired by Mailbox Providers for further optimisation of the email filtering. Due to this nature and expectation Security Vendor have a tough and strict policy to fight spam. This leads to a very hard definition of spam which is based on a huge amount of data that results from research and reputation, as well as fundamental technical best practices.

Around 90% (rough estimation) of the email traffic is considered as spam – as the front row knight Security Vendor try to filter out the riskiest email content and provide recommendations to Mailbox Providers how to further process inbound emails. Known viruses, risky and published IPs or Domains known from suspicious brands on negative lists will be taken into consideration.

Some use Spam Traps for tracking and observing the email eco system and some also collect direct user feedback. The feedback from the Mailbox Provider also constantly develop and impact the spam definition of Security Vendor.


Meanwhile a lawyer may still only take the legal perspective into consideration, which basically may include the ways of email acquisition practices as well as data trading and data storage in compliance to the legal requirements. This is a much closer and narrowed definition than from the parties who work in the email eco system actively on a daily basis.


To me there is not the one definition of spam and that will continue challenging the whole email eco system. This is quite obvious if you review the different perspectives described beforehand.

The definition of spam is highly influenced by clear spam factors that can be described and observed, but regional or cultural effects also influence the understanding or definition of spam very much.

Finally, it needs the understanding that all parties need to work together to fight spam and fulfil the different expectations and definitions of spam. There is no right or wrong about the different perspectives – but what all definitions have in common is the statement from the beginning:

“Spam is unwanted email in the inbox!”

Every party who wants to play a role in the email eco system needs to make efforts to understand the “unwanted”. This is the key and the biggest challenge at the same time.

Coming next

In a series of future blog post we will go further into details of different key topics related to spam to help developing a better understanding.

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