Simple Mail Transfer Protocol in a Nutshell

Hello everyone, TGIF!!! In this article, we're going to talk about SMTP. SMTP stands for Simple Mail Transfer Protocol, which is a protocol that is used for sending email. SMTP is basically a set of commands, that authenticates and directs the transfer of email. Now, a good way to remember what SMTP does is by looking at the acronym SMTP and associating it with sending mail to people. So as an example, when you write an email using an email client, such as Microsoft Outlook, and then when you hit send, the email travels from your computer to your email server using the SMTP protocol. This server is also known as the SMTP server. And this is what's configured in your email client. So for example, if you're using Gmail, the SMTP server address would be smtp.gmail.com. And then your SMTP server will send a message to the recipient's email server, also using SMTP. The email will stay on the recipient's email server until the recipient logs into their email account and downloads the email using POP or IMAP. Or they can just view the email on the server by using webmail. 

Now SMTP uses the TCP protocol and if you're not familiar with what TCP does, well, TCP is a connection-oriented protocol, and it guarantees the delivery of the email. Now, this is assuming that the destination email address is correct and still exists. But if for some reason that the email that you sent does not reach its destination, so for example, maybe you misspelled the email address, or the email address no longer exists. So if this happens, you'll get that familiar mail delivery error in your mailbox, informing you that the email you sent failed. And just like POP and IMAP. SMTP is also configured in your email clients, such as Microsoft Outlook, Mozilla Thunderbird, or your mobile device. So for example, if you're using Gmail, you would use SMTP gmail.com and the outgoing server settings in your email client. And this is also known as the SMTP server setting. This setting tells your email client where it can send the email to. 

In conclusion, SMTP is similar to a mailman, the mailman picks up the mail from your mailbox at your home, and then finds the correct route, and then delivers it to the destination mailbox.