It communicates with the Mail Submission Agent (MSA) to obtain emails that have been sent by a Mail User Agent (MUA), which is the mail client.
So how does an MTA differ from an SMTP server?Ī Mail Transfer Agent (also known as a mail relay) is software that’s installed on an SMTP server. SMTPĮarly on in this article, I mentioned that the MTA plays a part in sending email through SMTP. And once they arrive at their destination, they are converted back into their original format. SMTP uses an add-on protocol known as Multipurpose Internet Mail Extension, or MIME, to encode all non-text data into text format.Īll your images and other attachments will be converted to text before being sent through SMTP.
However, you can easily use the SMTP protocol to send emails with attachments. SMTP can only transfer text - it can’t send images or any other attachments. What Type of Emails Can You Send with SMTP? A transactional email is an email that’s automatically sent when a user action (e.g., account creation, feedback/comment, purchase receipt, download, etc.) happens on your website. Using the end-to-end method with SMTP servers really helps if your business regularly sends transactional emails. While this means most of the emails you write are sent using the end-to-end method, there’s one particular type of business email that benefits from this:
The store-and-forward method is used to communicate with email addresses within an organization, such as coworkers or students whose email addresses are part of the same domain (e.g., or end-to-end method is used for outgoing messages to addresses based on a mail server outside the organization. The Simple Mail Transfer Protocol model consists of two types: Once the domain and username are recognized, the email message is forwarded to the recipient’s POP3 mail server or IMAP server. The receiving SMTP server verifies the incoming mail. Then, the sender’s server connects to the receiver’s server and transfers the mail. The MX record points to the receiver’s mail server. However, if the two domains are different, the server will communicate with the Domain Name System (DNS) and obtain the receiving domain’s MX record via a DNS lookup. If they do, the email is sent immediately to the receiver’s inbox, and the email can be retrieved via POP3 or IMAP. Then, the Mail Transfer Agent (also known as a Message Transfer Agent) checks to see if the email addresses of the sender and receiver originate from the same domain. An SMTP command consists of alphabetic characters, and the server responds with numeric codes.ĭuring the TCP connection, the mail client transfers the following information to the server: Once the SMTP connection (which uses a TCP connection) is established with the mail server, an SMTP session begins.ĭuring this session, the SMTP client communicates with the outgoing server using various SMTP commands, like HELO. It finds the domain’s SMTP server by doing an MX record lookup on the domain. When a user wants to send an email, the email client (an email application like Gmail, Yahoo, or Outlook) opens an SMTP connection to the domain’s SMTP server. Here’s all the information you need to know about the Simple Mail Transfer Protocol: 1. However, for those of you interested in learning what goes on behind the scenes every time you click “Send,” read on: A.
So if you just want to learn how to set up your own SMTP settings, click here to skip this section and jump to my walk-through guide. Fortunately, you don’t have to know how SMTP works to use it. Note: The following sections can be slightly technical, as understanding how SMTP works can be quite complicated. Let’s take a quick look at how the SMTP email protocol works: While there are several different protocols in place today, SMTP is one of the most widely used outgoing email protocols. It’s part of the application layer of the TCP/IP (Transmission Control Protocol/Internet Protocol) network model.Īn email protocol is a set of rules that help you exchange information between email accounts. Simple Mail Transfer Protocol ( SMTP) is an email protocol used to send email messages from one email account to one or more email addresses.
Interested in learning about how SMTP works?