Understand what it is and how it works

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A blocklist is a tool used in SMS Marketing to protect users from unwanted messages. In practice, it works as a filter that prevents certain numbers or content from being delivered to the recipient.

In Brazil, operators and Anatel monitor spam reports and, after analysis, can include senders in a blocklist. This way, you avoid receiving unauthorized promotional messages, scams and abusive content.

Additionally, SMS sending platforms like Disparo Pro offer a feature called opt-out, which automates this process: if the user responds with keywords like “unsubscribe” or “stop,” the system automatically blocks the number from the sending database. This respects the customer’s wishes and maintains the company’s reputation.

And, of course, if you want to know more about blocklists in SMS marketing, continue reading with Disparo Pro and find out more!

What is a blocklist in the context of SMS Marketing?
In the context of SMS Marketing, a blocklist is a tool used to restrict the sending of text messages to certain phone numbers.

These lists are made up of contacts who, for different reasons, no longer wish to receive promotional messages or who have been identified as targets of inappropriate campaigns .

In practice, if a number is on a blocklist, any attempt to rcs data israel send an SMS to that contact will be automatically blocked by the operator's system or by the sending platform used by the company.

The blocklist is a way to ensure that messages only reach those who really want to receive them, protecting users and the reputation of brands that use SMS as a communication channel.

How does a blocklist work in practice?
In practice, a blocklist works like an automatic filter that blocks the sending of messages to certain numbers . When an SMS is sent, the platform checks whether the recipient's number is on the block list. If it is, the message is not delivered.

This happens in two main ways:

Manual addition: when the user requests to unsubscribe or the company itself decides to block the number, for example, after an opt-out request with words such as “exit”, “stop” or “cancel”.
Automatic addition: when the operator or regulatory body identifies abusive practices, such as spam or excessive sending, and blocks the sending number preventively.
>> Disparo Pro, for example, offers automated opt-out functionality, in which the system identifies keywords in users' responses and automatically adds contacts to the blocklist, avoiding the need for manual configuration.

Who is responsible for managing blocklists in Brazil?
In Brazil, blocklist management involves different agents. Telephone operators are responsible for implementing filters and mechanisms that prevent the sending of unauthorized messages.

SMS sending platforms, such as Disparo Pro, offer their own features for sending control, opt-out and contact blocking.

Furthermore, consumers also have an active role, being able to unsubscribe from campaigns directly through messages received or by registering on services such as Do Not Disturb, maintained by operators.

How does Anatel control unwanted messages?
Anatel (National Telecommunications Agency) is the regulatory body responsible for establishing standards and supervising the telecommunications sector in Brazil.

In the context of SMS Marketing, Anatel acts by defining good practice rules, such as the obligation to offer opt-out and time limits for sending promotional messages.

The agency also works in partnership with operators and platforms to combat abuse, punish companies that disregard the rules and preserve consumer rights.

What types of messages can lead to a number being blocklisted?
Messages that are considered abusive, unwanted or out of line may result in a number being blocked. This includes content that is considered spam, i.e. unauthorized mass mailings.

This category also includes repetitive messages sent with high frequency, without the recipient's consent, and sensitive or misleading content, such as phishing, misleading promotions or messages with malicious links.

Furthermore, messages sent outside the hours permitted by regulation or without the opt-out option are also considered inappropriate.

When a user feels uncomfortable, they can report the message to the operator or regulatory bodies, and this results in the sender's number being included in the blocklist, harming future campaigns.

How is a number included in a blocklist?
There are two main ways for a number to be included in a blocklist: manually, by user request, or automatically, by operator monitoring systems and SMS sending platforms.

In the case of opt-out, for example, when a user responds to a message with words such as “exit”, “stop” or “cancel”, the system identifies this request and automatically blocks the number in that company's contact database.

In cases of complaints, operators analyze the reports and, if the messages are not in accordance with Anatel's standards or show typical spam behavior, the number can be blocked preventively.