The digital world works in a similar way to the physical world. Just as a letter must follow specific rules and travel a defined route to reach its recipient, emails also follow a set of rules established by servers to be sent and delivered correctly.
Sending emails remains one of the most effective means of communication, both for personal use and for business marketing strategies.
However, many people are unaware that behind this seemingly simple process, there is a fundamental protocol that enables the exchange of messages: the Simple Mail Transfer Protocol (SMTP). Without this technology, sending emails as we know it today would not be possible.
In this content, we will explain what SMTP is, how it works, and what advantages it offers. In addition, we will provide tips to help you choose the most suitable service and one of the 5 best platforms available on the market.
What is SMTP?
SMTP (Simple Mail Transfer Protocol) is the protocol responsible for sending emails. Created in the 1980s, a period when the internet was beginning to establish itself as a global communication network, its main function is to ensure the reliable transmission of messages to their final destination.
It is essential not to confuse it with transactional SMTP, as their functions are distinct. SMTP acts in sending emails, ensuring that the message is transferred from an email client to a server and then forwarded to the destination server.
This process occurs within a client-server model, where the client (such as an email application) initiates communication so that the message can be sent.
However, SMTP ends its operation as soon as the message reaches the recipient’s server. From that point on, protocols such as POP3 or IMAP come into play to enable the receipt and synchronization of email in the user’s inbox.
How SMTP works
When an email is sent, the SMTP server receives all the message information and adjusts it according to the email transfer protocol standards. It then forwards the content across the network, ensuring its transmission.
In simple terms, the SMTP protocol takes the email message you compose in your email client and ensures that it is correctly delivered to the recipient’s server. Here is a summary of this process:
- Creating the email;
- Connecting to the SMTP server;
- Sending the message;
- Delivery to the destination.
SMTP uses a series of basic commands to enable communication between email servers. These commands are executed in order whenever an email is sent, ensuring that the message is transmitted correctly and reaches the destination server without failure.
Some of the main commands are:
- HELO/EHLO: used by the email client to identify itself to the SMTP server;
- MAIL FROM: informs who the sender of the message is;
- RCPT TO: indicates the recipient’s email address;
- DATA: marks the beginning of the message content, which is followed by the text of the email, and ends with a period (.).
- QUIT: ends communication between the email client and the SMTP server.
What is the importance of SMTP?
Despite the growth of instant messaging apps and social networks, email remains one of the main means of communication on the internet, especially in the corporate environment.
In addition to enabling the sending and delivery of messages, the SMTP protocol plays an essential role in verifying the authenticity and integrity of emails, helping to prevent fraud, spam, and cyber attacks.
Its importance goes beyond personal and business interactions, as it is also fundamental to email marketing strategies, where effective message delivery is indispensable.
For this reason, several marketing automation, CRM, and email delivery platforms use advanced SMTP servers, ensuring higher delivery rates and preventing relevant messages from being classified as spam or not even reaching their recipients.
How to choose the best SMTP tool?
Once you have a better understanding of what SMTP is and how this protocol works, selecting the most appropriate SMTP service requires analyzing several essential criteria. To make this choice easier, we have compiled the main factors that should be considered:
- Delivery rate: check the average email delivery rate for each service. The higher the rate, the more efficient your messages will be.
- Scalability: make sure the solution can keep up with your business growth and handle a large volume of mailings as demand increases.
- Ease of use and integration: choose a service with intuitive configuration that easily connects to the tools and platforms already used by your company.
- Customization and segmentation: choose a provider that offers advanced options to customize and segment your campaigns, making your messages more assertive.
- Technical support: fast and efficient service can make all the difference in troubleshooting and optimizing the service.
- Security: prioritize solutions that feature robust authentication and encryption, ensuring the protection of data and communications.
- Cost-effectiveness: analyze the available plans, considering prices, features, and limitations to choose the best option for your needs.
- Reputation and reviews: research user opinions and reports on their experience with the service to get an overview of the quality offered.
Best SMTP tools
We have compiled a list of the main SMTP services to help your company send large volumes of transactional emails with complete security.
You will get an overview of each platform, exploring its benefits, possible limitations, as well as information on prices and available plans. Follow along and discover which of these solutions can boost your communication.
1. JivoChat
JivoChat is a multichannel customer service platform that offers an innovative solution for email communication between companies and customers. One of the main advantages of JivoChat Email is its ability to consolidate all email interactions in a single environment.
Instead of accessing multiple inboxes separately, agents can manage multiple email accounts (such as suporte@empresa.com and vendas@empresa.com) in one intuitive interface. This makes it easier to stay organized and reduces the risk of missing important messages.
In addition, the solution synchronizes emails with other channels on the platform, such as live chat, WhatsApp, Telegram, Viber, and social networks. This way, the customer’s complete history is accessible in one place, allowing for personalized and more agile service.
Highlights:
- Automatic Responses
- Smart Forwarding
- Reminders and Follow-ups
2. Brevo
If you are looking for an SMTP server, Brevo may be the ideal choice for you. With the ability to send up to 9,000 emails for free, it stands out from other SMTP providers, although it does have a daily limit of 300 emails.
Brevo is not limited to sending marketing emails; it offers a complete digital marketing package, including a CRM, newsletter templates, and even features such as live chat, all available at no cost.
If you are looking for a comprehensive marketing platform, Brevo may be exactly what you need.
Advantages of Using Brevo:
- Complete marketing solution
- Free plan
- Support in Portuguese
3. SMTP2GO
SMTP2GO is another SMTP service that facilitates sending and monitoring emails, providing a practical and hassle-free experience.
Its main advantage is the guarantee of a high delivery rate, even in situations of unstable internet connection, ensuring that your messages reach their destination without interruption.
In addition, the platform identifies and notifies you of possible irregularities in your account, such as an unexpected increase in email rejection rates, allowing you to make quick adjustments to avoid negative impacts.
Highlights:
- Detailed and intuitive reports
- Spam verification
- 24/7 technical support
- Automatic SPF and DKIM configuration
- Integrated unsubscribe link
4. Mailchimp
Mailchimp allows you to efficiently send large volumes of transactional emails, ensuring speed and reliability. In addition, the platform offers a wide variety of digital marketing tools, including CRM and website builder.
With Mailchimp, you can easily configure SMTP and customize your messages with unique headers. The platform also offers analytical reports that allow you to monitor delivery rates, recipient engagement, and your account’s reputation.
5. SendPulse
SendPulse offers an excellent SMTP service, as well as an integrated set of essential tools for businesses, such as email marketing, chatbots, landing page builder, smart pop-ups, and much more.
With SendPulse’s SMTP service, you can easily send large volumes of transactional emails to your customers.
In addition, the platform provides detailed reports that allow you to monitor important metrics such as the number of emails sent, conversion rate, click-through rate, unsubscribes, and more.
Most popular SMTP ports
The ports used in SMTP fall into two main categories: submission, responsible for sending messages, and relay, which establishes connections between servers. Among the main ports available, the following stand out:
- 25 – Created in 1982, it is one of the oldest and most widely used within internal networks. However, many providers block its use to prevent spam.
- 465 – Designed for secure connections between SMTP servers, it is used to send emails with SSL/TLS encryption.
- 587 – Currently the most recommended for sending emails, as it offers a higher level of security.
- 2525 – It has similar functions to port 587, but its availability depends on each server.
Currently, manually configuring these protocols, including SMTP, is rarely necessary. This is because most email applications on mobile devices and web platforms already have this configuration predefined.
Frequently asked questions about what SMTP is
What is SMTP?
SMTP (Simple Mail Transfer Protocol) is a protocol used to send emails over the internet. It defines the rules and processes that must be followed so that messages are transmitted efficiently between email servers.
How does SMTP work?
When you send an email, SMTP is responsible for:
- Send the message from the sending server to the recipient’s email server.
- The recipient’s server then receives and delivers the email, usually using other protocols such as POP3 or IMAP for final delivery.
- SMTP only handles sending messages, not receiving or reading emails.
What is the difference between SMTP, POP3, and IMAP?
- SMTP: Used to send email messages.
- POP3: Allows you to download emails to your computer or device and usually deletes them from the server after downloading.
- IMAP: Also allows you to download emails, but with the advantage of keeping messages synchronized across multiple devices without removing them from the server.
Is SMTP secure?
The basic version of SMTP does not offer encryption, which can make messages vulnerable. To increase security, it is recommended to use SMTP with authentication and SSL/TLS encryption, which protect the content of the email while it is being transmitted.
What is SMTP authentication?
SMTP authentication requires you to enter a username and password to send emails, which helps ensure that only authorized users can use the email server for this purpose.
How do I configure SMTP in my email service?
- Go to your email client settings (such as Outlook, Gmail, Thunderbird, etc.).
- Add your email provider’s SMTP server (usually something like smtp.yourprovider.com).
- Enter the correct port (587 or 465) and configure authentication by providing your username and password.
- Enable SSL/TLS encryption if necessary.