Difference Between SMTP and LMTP

SMTP and LMTP are the transmission protocols. The full form of SMTP is Simple Mail Transfer Protocol, as the name suggests; it simply transfers the email messages to another over the internet. It works over the wide-area network and the port 25 used in SMTP. The full form of LMTP is a Local Mail Transfer Protocol that transfers email messages to another locally. It does not work over a wide network, and port 24 is used in LMTP. In this article, we will cover the explanation of SMTP and LMTP and their differences.

What is SMTP?

SMTP is a simple mail transfer protocol. In SMTP, we send email messages to one another over the internet. But in SMTP, we add one receiver’s email address at a time to send the message. If we want to send the messages to multiple recipients, we can add the email address to CC and BCC. They have more storage and also work on a WAN, which means we send the message to a receiver outside the internet. It is also responsible for handling errors while sending messages, like if a person enters the wrong email address and sends the message “message not delivered.”.

Working of SMTP

fig: SMTP

• The first process of working with SMTP is the mail composition, where the email consists of a body and subject. In the body section, we can write the content and subject that represent the heading.

• The second process is the mail delivery, which requires the receiver’s email address, like person@gmail.com, where person represents the username and gmail.com represents the domain name. If the receiver domain name and sender domain name are the same, then the Mail Transfer Agent (MTA) connects to the server and transfers the message, but if both domain names are different, then the MTA finds the domain name in the DNS and, if found, connects to the server and transfers the message.

• The third process is that if the server receives the email, it goes to the mail delivery agent. The MDA waits for the email until the user gets it.

Components of SMTP

• MUA: MUA stands for Mail User Agent, which is useful for sending and receiving messages.
• MSA: MSA stands for Mail Submission Agent that communicates with MUA to transfer the email messages.
• MTA: MTA stands for Mail transfer agent that transfers the mail to another with the help of SMTP.
• MDA: MDA stands for Mail Delivery Agent, which is useful for delivering mail to the local system.

Advantages of SMTP

• Easy to use and implement.
• It is used in a wide-area network.
• They have more storage.
• It is easy to handle bulk mailings.

Disadvantages of SMTP

• They have a bigger problem in terms of SMTP security.
• Sometimes the delivery of a message gets delayed.
• Blocking of SMTP ports because of firewalls.

What is LMTP?

LMTP is a local mail transfer protocol. They do not have a mail delivery agent on the receiver’s side. They do not work over a WAN. It transfers the email messages from one mail service to another locally. In LMTP, port 24 is used. It works in the same mail server environment. In LMTP, we send the email messages to multiple recipients.

Working of LMTP

fig: LMTP

Local mail transfer protocol that transfers the email to another local The aim of LMTP is to decline a message that does not reach its destination. The LMTP syntax depends on ESMTP, i.e., the extendable simple mail transfer protocol. ESMTP is responsible for sending and receiving messages over an IP network. There is an LMTP server that connects between sending and receiving messages.

Advantages of LMTP

• It is easy to use.
• It is more secure.
• In LMTP, there are two mail servers for communication.
• It easily handles errors while sending messages.

Disadvantages of LMTP

• They do not have TCP port 25.
• They do not have much storage.
• It immediately declined a message that did not reach the recipient.

Difference Between SMTP and LMTP

Characteristics	SMTP	LMTP
Defination	SMTP is a simple mail transfer protocol; as the name suggests, it simply transfers email messages to another over the internet.	LMTP is a local mail transfer protocol that transfers email messages to another locally.
Ports	In SMTP, Port 25 is used	In LMTP, Port 24 is used
Supports WAN	It Supports Wide Area Network	It does not Support wide area network.
Support Servers	It supports different mail server for communications.	It supports same mail servers for communication.
Supports Bulk emailing	SMTP supports bulk emailing	LMTP does not supports bulk emailing.
Recipients	In SMTP, we send the multiple recipients at once, like if we add the multiple receiver’s email address so that we put in BCC and CC.	In LMTP, we easily send email messages to multiple recipients.
Server Required	SMTP Server required in SMTP	LMTP server required in LMTP

Frequently Asked Questions on Difference Between SMTP and LMTP – FAQs

How many ports LMTP and SMTP support?

LMTP uses port 24 instead of port 25. In SMTP 25,587,2525, where port 25 is the standard SMTP, port 587 is the default port; it supports TLS, and port 2525, we can’t say officially SMTP port, but cloud hosting providers still support this port.

Is LMTP support authentication?

LMTP does not support authentication fundamentally like SMTP. In LMTP, we use MTA for sending and receiving mail. But in the case of authentication, we use MTLS to authenticate the connection. Since MTLS is a mutual TLS, the API is secure.