What Does an SMTP Server Do?

Practically everyone uses email; 281 billion are sent per day, after all. It’s a valuable communication tool, especially with prospects and clients.

Surprisingly, for something so widely used, email is not very understood by most people. To help you grasp the inner workings of email, we’ll explain what an SMTP server is and how it’s used for email.

SMTP: explained

SMTP stands for “Simple Message Transfer Protocol.” This is the protocol your email client uses when you have outgoing messages. In relation to a physical mail system, the SMTP as a service would be the mail truck, since it’s what transports emails from your inbox to the recipient’s inbox.

SMTP server: explained

Now that you know what an SMTP service is, we can explain what an SMTP server is. Like a regular server, it powers the protocol. It takes the information it has and gives it to other computers, which lets it find the correct inboxes for delivery.

But SMTP servers don’t work in both directions; they can only deliver outgoing mail, not receive incoming messages. The counterpart for receiving emails would be POP3 or IMAP.

MORE: Know SMTP Pricing

How an SMTP server works

Although the process of sending an email appears to be instant, there are a few steps outgoing mail has to take before it reaches the recipients’ inboxes. Here’s the entire process:

  1. In your email client, you fill out the form (recipient’s name, address, and your message)
  2. and press send.
  3. Your email client connects to your domain’s SMTP server. Once it’s connected, it sends all the email information to the server. This includes the email addresses and content.
  4. If both addresses are from the same domain name, then there’s no relay needed. Your message will be sent to the recipient’s POP3 or IMAP server. If the domain names are different, the SMTP relay service will have to relay your message. It’ll get the recipient’s IP address by accessing the DNS (Domain Name Server).
  5. Now that your SMTP relay server has the recipient’s IP address, it can connect to their SMTP server.
  6. The recipient’s SMTP server scans your email. If it’s from a non-blacklisted IP address or domain, then it’ll accept it into the POP3 or IMAP server.

Use a third-party SMTP server provider

Using a third-party free SMTP server provider is highly beneficial for your organization. You’ll be able to send both bulk and transactional emails without fear of them ending up in spam folders. Not only that, but you can get protection against malware too.

MORE: Email pricing for providers

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