AntiSPAM: What are spam filters and how do they work?

Interestingly, the word spam has a very different origin than many of us might think. This name comes from a brand of canned meat, which American soldiers received from their relatives during World War II.

But today in computer science this has acquired a different name; it is known as an unsolicited message that generally refers to the sale of products and services without authorization. It is therefore common to receive notifications that are not of personal interest.

Previously, these were only addressed or rather known in emails, but this has expanded to other platforms such as blogs, instant messaging, social networks and even mobile devices. To learn more about this, in the next tutorial we will explain step by step what it is, how spam filters can help you and more.

What is SPAM or junk mail in my inbox?

As mentioned above, its name comes from an old brand of canned meat. Although, it currently has a very different definition and is junk mail. Referring to unsolicited or unwanted messages. Mainly of advertising type or those that are sent in a massive way.

In the category of spam you should also add the messages that are sent for fraudulent purposes or malicious emails. These usually contain false information to carry out scams, so they are only intended to get personal data from the recipient.

However, this type of mail is not only limited to e-mail today, as social networks or instant messaging such as WhatsApp are also affected. That’s why we have to be very attentive to what we receive on many occasions.

What is an AntiSPAM and what is this type of program used for?

When we talk about anti-spam programs, whether for computers or mobile devices, we mean that they allow their users to delete or block all mail that the user considers unwanted, or that the person has marked in the same way.

What can they be used for? Simple, they serve to keep your email inbox, your WhatsApp, Facebook Messenger, Twitters or other applications you use to communicate, free of these malicious and annoying ads.

It should be noted that this is not only allowed by programs or applications, it can also be configured with email services such as: Gmail, Outlook and others, to block and send to the folder of deleted messages, everything you have considered as spam.

How does an Anti-SPAM work? Main functions

They work by scanning all the messages that come to you, where they in turn are rated around certain characteristics. Depending on the rating, the communication may or may not be considered spam.

After analyzing the entries, they can be: blocked, deleted or sent to the “Spam” folder. When they are marked as “Deleted”, this is not entirely true, as they are sent to the corresponding folder.

No such notice is, under any circumstances, removed entirely, as there may be instances where messages that are not spam are listed in this way. So to prevent them from being deleted, they are archived until you review them and you are the one who cancels or recovers them.

What are the types of Anti SPAM that exist and how do they differ?

There are two main types of anti spam, these are:

  • Those that identify the spam message from features they contain. This is reflected through a study, where they are reviewed and qualified. Depending on the qualities, they will receive a score, and the higher it is, the more likely they are to be considered or not.
  • The anti-spam filters that identify them use statistical approximations. Esto es algo similar a lo anterior. Pero en estos casos es mucho más preciso. No obstante, necesita de una ayuda previa, esta consiste en que el usuario de forma manual identifique los mensajes de este tipo.
    So you learn from their characteristics, to block in the future all those that are catalogued as such with the details you learned previously.

In addition, we can see other varieties of filters, such as:

Bayesian antispam filters

Bayesian filters work mainly through experience, and they learn from those messages that users themselves mark as such. So they need other people to be effective and improve. That is to say, if the user qualifies an e-mail as such, what he will do is compare those marked e-mails with others and create a database to discard them at once.

This type of filter can raise the alert through words or the use of some effects, for example: the word “FREE” is capitalized or the use of brightly colored, bold or yellow shaded fonts.

The lists they use are generated by detecting patterns, starting from the e-mails that were manually marked as spam. Therefore, it is possible that in some cases, mail that is not spam is marked as such and appears in the spam folder.


Blacklists exclude any messages coming from certain IPs. These are databases that throw up addresses where bad actions have been performed, such as mass mailing.

It works by the mail servers that check if it is hosted there, so they know whether to accept or reject the mail received. The problem arises when it cannot differentiate whether these are sent voluntarily. So you may find yourself in one of them for no reason.

The reasons may be as follows:

  •  You may have sent some messages to a spamtrap or trap mail, these are mails that the mail service providers have created and that have no activity. They use it as a warning method, to catch spammers.
  • Your email has been hacked and messages have been sent automatically.
  • Your computers were infected by some virus that constantly sends emails to anyone.

Email Firewalls

Firewalls, also known as firewalls, are nothing more than systems that restrict unauthorized access to certain elements. They work by rules that are established by the provider and administrator of the provider. They usually use a combination of Bayesian filtering, blacklisting and others to prevent spam.

So this will make all messages received or sent, pass through the firewall that will examine each message, and not meet any of the security criteria will be blocked.

Challenge/Response filters

Although these are not as widely used, there are many who still implement them. Here’s how it works; if you send an email with this filter, and the contact is still not on the friend list or in that person’s notebook, you will be considered a stranger. So you will be labeled as a spammer.

This is to check whether you are or not, what it does is that you are sent an automatic answer with a question to be answered or some link to be entered, to prove that you are not a robot. In case you are tagged as such, all you have to do is talk to the receiver to be included in their list.

Anti-spam filters based on your reputation

Reputation depends, as it says, on your position, that is to say, on the scores that the sender’s identification acquires. This filter is based on the sending IP address and the name of your domain used to send the e-mails. If you do not have a reputation, they will be watching you, as this will measure your performance and that of your followers.

If you get a good reputation, you’ll get a good percentage of the people who open your email campaigns and links.

Why should I use a spam protector? The dangers of SPAM and how to avoid it

It is important to use an anti-spam program or application, because they allow you to keep your e-mail accounts more secure. So that you can safeguard your personal information and the status of your computer.

You should know that there are not only unwanted emails from those sent as a repetitive or recurring message. There are also those that may contain malware intended to steal your information or cause damage to your equipment. Such damages can be solved or in the worst case not. It is common for inexperienced users or those who are careless.

Similarly, they save time by not having to check these types of emails, since even senders using fraudulent or untrustworthy accounts can be identified. The best way to avoid this is through any anti spam program.

We suggest that if you do not have them and you receive any suspicious mail, never open the document or the link attached to it. 

On what platform can we be victims of SPAM besides email?

There are many platforms where you can become a victim of spam. You can connect from any device to almost any platform.


Blogs are usually sites where spam can exist, because users perform annoying practices to gain recognition, intimidate, or for unethical purposes.

Social networking

Sites such as Facebook, Twitter, Instagram, YouTube and many more often spam pages you don’t follow, other users, or other similar content.


These types of websites are intended to share information or discussions primarily. But, there are cases where malicious users use it to spam various things.

Instant Messaging

Believe it or not, instant messengers can get spammed, and not just through text messages. You can also receive them via platforms such as WhatsApp, Facebook Messenger, Skype and others.

Within gaming platforms

It is common for online games to have options to add friends or send messages. So that by these means can also be sent junk messages that only generate discomfort, or that can steal the user’s information.

In short
Spam can affect virtually any area. Whether for annoying purposes, to discredit or for more dangerous purposes. Therefore, it is very important to be aware of this type of modality.

This post is also available in: Português (Portuguese (Brazil))

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