What is a mail server?

In today’s lesson, we will focus on the purpose and definition of a mail server. This is a very important server and probably one of the first to consider when designing your new infrastructure.

Without even thinking about it, you are receiving and sending emails while reading those lines. Email goes from you to another point in the world in a matter of seconds. We take it for granted, giving little thought to how this actually happens, but this is a complex process that is accomplished with the help of a mail server.

A mail server is a computerized analogy of the neighborhood postman (only slightly faster), but while an email appears to be sent from one PC to another in the blink of an eye, it actually jumps across multiple servers. of mail around the world until it reaches its destination. Without those servers, you would only be able to send emails to the same addresses only on matching domains.

There are 2 types of categories for mail servers: outgoing mail servers and incoming mail servers.

Outgoing uses a protocol called SMTP (Simple Mail Transfer Protocol). Incoming mail servers can be POP3 (Post Office Protocol vs. 3) or IMAP (Internet Message Access Protocol). POP3 servers store emails on local hard drives or PCs, while IMAP stores emails on servers, but this is kind of boring.

Back to our explanation: Basically, what happens is that when you hit send on your email, whether it’s Outlook, Gmail, Yahoo, or any other email service, the email client connects to your domain’s SMTP server. The email client then contacts the SMTP server (remember, this is for outgoing mail), giving it your email address, the recipient’s email address, and the body of the message along with any attachments.

The SMTP server processes the recipient’s email address. If the domain is local, no routing is needed and it goes directly to the domain’s POP or IMAP server. If the domain is different, the SMTP server will need to communicate with the server in the other domain.

Along its long journeys, the SMTP server must meet the DNS server (which is the server responsible for converting email addresses to IP addresses; we’ll talk about DNS servers in a future). The DNS server will translate the email address to an IP address, which is the language that the DNS server speaks fluently.

Now that the SMTP server has the proper recipient IP address, you can connect to the recipient’s SMTP server. This is not done directly, and the message is usually routed through a series of other SMTP servers until it reaches its destination. It’s definitely not an easy journey for such a fragile message, but most of the time they make it through.

And finally, the recipient’s SMTP server receives the message, scans it to confirm the domain and username (this step is important when you’re filtering spam), and if all is well, forwards it to the POP server to be read. . Once you hit the email, it’s downloading. POP will generally download it to local hard drives, while IMAP will use a server to download the message.

This is basically the secret of the mail server: a simple but really complex task behind the scenes.

Some may ask “What does this have to do with my business? I’ll just use Gmail or Yahoo. It’s free.” Yes, it’s free, but there are those who require a lot of space, usually companies, and those often have to invest in servers.

In addition to purchasing the servers, you’ll need to have a way to receive and transmit email, and set up your own email settings and filter.

To that end, you could be using one of the 2 most popular programs like Postfix or Microsoft Exchange. Such programs facilitate the process behind the scenes.

After all, a mail server is a server that takes care of sending and receiving emails at the back of the process, away from the end user. Their job is to send the messages to the correct destination, receive messages from the correct senders, filter out any inappropriate content, and store the emails on file if necessary. Because it seems easy to an end user, it’s often taken for granted, but it’s still smart to have a basic understanding of how mail servers work.