What is SMTP?
SMTP, which stands for Simple Mail Transfer Protocol, is an email protocol used for sending email messages from one email account to another via the internet.
Email protocols are sets of rules that let different email clients and accounts easily exchange information, and SMTP is one of the most common ones alongside POP and IMAP. It is also the only dedicated protocol for sending emails. Most email clients including Outlook, Apple Mail, Gmail, and Yahoo Mail rely on SMTP to "push" or send messages from a sender to a recipient.
What is an SMTP server?
Like all servers, an SMTP server is an application that provides a service to other applications within a network, called clients. Specifically, an SMTP server handles the sending, receiving, and relaying of email.
You can think of servers as your real-life post offices. When you send a letter from city A to city B, it first reaches a local post office in city here, it gets processed and sent on the post office in city B, which is in charge of delivering it to its final destination. The same happens with SMTP servers though instead of taking days, the process takes a few minutes at most.
You might have also come across the term SMTP port. Those are the communication endpoints that handle the transfer of email data over SMTP as it moves through a network, from one server to another. We cover those in detail here.
How does SMTP work?
The best way to explain how SMTP works is to go over the sending process, the individual rules and commands that power it, and the errors you may encounter. Fair warning: This is where things start to get technical. Still, we'll do our best to condense this protocol down into easy-to-digest chunks.
Once an SMTP server is established, email clients can connect to and communicate with it. When the user hits "send" on an email message, the email client opens an SMTP connection to the server so it can send. (The SMTP connection is built on something called a TCP connection, which stands for Transmission Control Protocol.)
From there, the SMTP client uses commands to tell the server what to do and transfer data, like the sender's email address, the recipient's email address, and the email¡¦s content. The Mail Transfer Agent or Message Transfer Agent (MTA) checks to see if both email addresses are from the same email domain, such as gmail.com:
- If they are, it sends the email right away
- If not, the server uses the Domain Name System (DNS) to identify the recipient's domain and then send it to the right server.
SMTP Mailer Plugin For WordPress
SMTP Mailer is the easiest SMTP plugin for WordPress. It allows you to configure an SMTP server to send email from your website. SMTP Mailer enhances the default WordPress mail ("wp_mail") function by letting you connect to a remote SMPT server to send an email instead of doing it from your web server. This reduces heavy load from your server and increases email deliverability.
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