deliverability letter

Relay Your Traffic Through an SMTP Server: Solutions for High Frequency Marketing

Thoughts by Aleksandar Miceski • Writer Bento

Have you experienced deliverability issues with simple emails, like password changes or purchase receipts? Or perhaps transactional emails are not the problem, but the ISPs of your clients are throttling the number of emails you can send in one batch.

Most of us in email marketing have been there at one point or another. These issues are complex, which is why you can’t find one solution for all of them. Rather, you can start to eliminate potential causes of failed authentication attempts, and SMTPs definitely facilitate email validation on a large scale.

You’ve probably encountered offers to use an SMTP server for your email marketing campaign. But did you know that “SMTP server” is sort of a misnomer? This is because SMTP is actually an application, and platforms extend an offer for you to use their services, hence the “server” part. So, let’s get into the details of what SMTP is and how it actually helps digital marketers.

What Is SMTP?

SMTP stands for Simple Mail Transfer Protocol and refers to an internet standard for sending, receiving, and relaying messages. It’s a way to manage communication between mail servers by checking senders and receivers and associating them with domain names and internet addresses. This application was introduced in the eighties, and as you can imagine, it has undergone a series of modifications and updates since.

Its evolution is heavily involved with the history of the internet – from the time ARPANET had fewer than 50 hosts to the net we know of today. This is why some of the standard practices for handling email transfer using SMTP have become outdated and are not used anymore.

Still, there are plenty of benefits that come with using a well configured and reputable SMTP provider, so let’s see what they are.

Benefits of SMTP for Digital Marketers

The modern SMTP has evolved since 1995 and is still very relevant for e-marketers. Drawing on its traditional role in processing data pertaining to email communication, the modern-day SMTP is one of the go-to filters for illegitimate mail. It’s how big ISPs (Internet Service Providers) protect their users. Too many safeguarding systems rely on SMTP for you to ignore it.

Proper email campaign management through a responsive SMTP serves to boost deliverability. They can aid you in cutting down spam notices and in keeping email bounce rates to a minimum. It’s quite straightforward when you think about it. SMTP is crucial for adopting up-to-date authentication specifications. So, if you are involved in high-frequency marketing, it will be easier for you to keep up with the constant changes in authentication policies. The same goes for validating the portion of your traffic that consists of transactional emails. This will soon reflect on customer retention figures, and of course, you will reach more potential customers.

Everyone has a choice

Many marketers that handle small amounts of traffic often will just use a basic SMTP server, maybe even their own private one, to send email. When you start sending more, you need to find a provider or set up servers yourself. You can easily find the instructions for your respective device and provider with the intent to configure the right SMTP server. Although, keep in mind that using a regular email address to send large email batches will cause problems very quickly.

The typical user has very strict limitations in terms of sending emails: concerning both the number of addresses you can reach in a day and the number of emails you can send to them within the same day.

Your average Joe is not aware of the imposed limitations because they’ve never tried to send a lot of messages to an excessive list of recipients. If you are crafting email marketing campaigns you already know better. This is one of the main reasons professionals go for SMTP servers – it solves so much of the issues regarding high-frequency campaigns.

SMTP Service Providers

There are many options to choose from when it comes to SMTP service providers. In essence, they let you use their server to send your campaigns. It’s why they are known as “SMTP servers”. You can pair your mail client to an SMTP server and improve deliverability. This is possible because issues with SPF or DKIM signatures or other DNS failures are checked.

Registration is usually done by choosing username, password, and protocol (SSL or TLS), and sharing SMTP server address and ports (25, 465, 587, 2525). These servers facilitate sending a lot of emails and some offers include real-time email tracking or advanced analytics, however, these perks can vary across platforms.

What’s With All Those Ports?

We all know that domain names actually replace a series of digits that are not as easy to remember. So, instead of entering a numerical address in the search box, we type in ““ to access a web page. One part of this numerical address is used to transfer email and is known as SMTP port.

You can easily find the port used by your service provider. If you are using an SMTP server, the configuration details will include info on the port. SMTP ports in use are: 25, 465, 587, or 2525. The first two belong to history, although port 25 is default and is commonly used for bounces that happen after the fact (email was delivered and then bounced).

Residential users have this port blocked because most of the spam is relayed through it. Without getting too technical, the SMTP port that is recommended for best deliverability is 587, particularly if it’s coupled with TLS encryption. The last port number (2525) is mostly used as a fallback option.

SMTP Server Protocols

Cryptographic protocols - SSL (Secure Sockets Layer) and TLS (Transport Layer Security) - are used to encrypt a given communication channel. In plain English, they ensure the traffic between a sender and a receiver is safe. SSL and TLS are used for encrypting different types of channels (for example, instant messaging), but in the context of SMTP, they refer to safe email transmission.

When the connection between two servers is set up, they need to exchange credentials to base their confidence on. This is done through a digital handshake, and in many ways, this process is similar to DKIM authentication (insert a link to DKIM email validation here), although TLS protocols operate on a much deeper level.

SSL was created in 1995 to protect any sensitive data shared between two servers. In essence, it employs algorithms to encrypt and scramble data in transit, so no one can snoop on vital information, like passwords. The TLS is practically an update, adapted to fit a more recent landscape. Sometimes the terms are used interchangeably, so if your provider is not offering TLS protocol, check what they exactly refer to when they use SSL, to get the most of the deal.

Final Thoughts

The capacity to reach a target audience, given all sorts of spamming, spoofing, and phishing traffic ISPs have to sort through, heavily depends on your sender reputation. It's not a simple problem and email marketing professionals have to employ a comprehensive approach to tackle deliverability issues.

Email authentication methods like DMARC (DKIM and SPF) will reduce your bounce rates, however, if you are dealing with a large volume of traffic, you need to look elsewhere. Such large campaigns would benefit from getting an SMTP server, especially if your traffic includes transactional emails. Other marketers successfully execute their campaigns with the help of SMTP servers, so why not explore the options if you want to reach more customers? It’s how email transfer was developed, so simply make it work in your favor.