an smtp relay is a protocol that allows email to be transmitted over the internet, from one server to another, for delivery. was first created in 1982 and is still the Internet standard that is widely used today.
an smtp relay is an email relay service that basically works in two steps:
-
receives the sender’s outgoing mail (ie your awesome Groundhog Days email campaign).
delivers it to the recipient’s local post office, another smtp server.
simple, right?
wait, but what is ’email relay’?
ok, maybe it’s not that simple yet. To break it down a bit more, let’s imagine the journey your normal postal mail might take to reach its destination:
Email relaying is the process of transmitting an email message from one server to another. In the image above, the local post offices would be the smtp servers and the mail transfer that happens between them is what we call ‘broadcasting’.
So, for example, when you send your latest “cute puppies looking for a foster home” campaign, your company’s smtp server relays your email to the server owned by your recipient. but if you were to send that campaign to someone with your same domain, there would be no ’email relay’ as your smtp relay server would not need to transfer the email to a different smtp server.
send through an smtp server with an email service provider
so what does this protocol look like when dealing with an email service provider like mailjet? Getting the most out of your own smtp relay server isn’t easy, so most companies that need to send bulk emails to their customers use smtp relay for easy maintenance and additional analytics.
Sending through an email service provider via smtp relay saves businesses from having to run their own mail server. as you can see in the diagram below, the email is created by the company or the sender and their server sends it to the mailjet smtp server to prepare it and send it to the recipients.
To combat spam, most webmail providers and email clients (ie gmail, outlook, yahoo, etc.) limit the number of emails you can send to different recipients per day. Since businesses that need to mass communicate with their audience often exceed this limit, they will need the services of a business-grade email delivery platform, such as mailjet.
an smtp relay provider can help businesses and organizations deliver large volumes of email without being mislabeled as spam or facing small sending limits.
Email service providers invest a great deal of resources in building their own email infrastructure to handle large volumes and work closely with major Internet Service Providers (ISPs) and email providers. to improve email deliverability and deliver these emails directly to the recipient’s inbox.
behind the scenes: smtp server trace
There is an additional layer of value to sending through an email service provider. with mailjet, before our smtp servers send an email, our system automatically adds link trackers into the body of your message. this allows you, as a user, to properly track opens and clicks after receiving an email.
mailjet also translates comments from isps (gmail, yahoo, aol, etc.), as each one communicates in their own way. our service saves developers time by turning this into an easily identifiable response, showing whether an email was delivered or bounced. These metrics make it easy for you to identify issues that could affect your email deliverability.
Would you like to know if a third party smtp relay service is the best option for your business? our email infrastructure handbook helps you understand the pros and cons of in-house and outsourced email infrastructure and find the best option for you
choose an smtp relay port
aha! another complicated aspect of the email world. To understand what smtp ports are and how they work, we need to take a step back and see what happens when computers talk to each other over the internet.
Let’s say you are trying to communicate with mailjet.com. in this case the domain name system (dns) is converting this to the real ip address which is hidden behind the site name. in the case of mailjet, this is 104.199.110.216. you can probably remember 4-5 ips like ours, but who can remember more, or really… who would?
an smtp port is one that is intended to be used for smtp connections. today, the most common smtp ports are 25, 465, 587 or 2525. this does not mean that they are the only ones , nevertheless. these few ports are the most used for this type of connection, and so they are almost always open, which means you should be able to get to your destination.
choosing the correct smtp relay port to use is really an important consideration when it comes to smtp. so much so that we already dedicated an entire blog to this. If you’re trying to decide which port to use, be sure to read our article which smtp port should I use? to see which one is best for you.
summarizing
Ultimately, smtp relay makes our lives as marketers much easier by handling all the heavy lifting on the backend so we can spend more time crafting content and the creation of our contact lists.
>
Still want to learn more about smtp relays? check out this episode of email explained. our mr. Technical Account Manager gives us 101 of what you need to know about smtp relay.