Disadvantages of SMTP

What is Simple Mail Transfer Protocol?

SMTP is an application layer protocol. The client who wants to send the mail opens a TCP connection to the SMTP server and then sends the mail across the connection. The SMTP server is an always-on listening mode. As soon as it listens for a TCP connection from any client, the SMTP process initiates a connection through port 25. After successfully establishing a TCP connection the client process sends the mail instantly....

SMTP Protocol

The SMTP model is of two types:...

Model of SMTP System

In the SMTP model user deals with the user agent (UA), for example, Microsoft Outlook, Netscape, Mozilla, etc. To exchange the mail using TCP, MTA is used. The user sending the mail doesn’t have to deal with MTA as it is the responsibility of the system admin to set up a local MTA. The MTA maintains a small queue of mail so that it can schedule repeat delivery of mail in case the receiver is not available. The MTA delivers the mail to the mailboxes and the information can later be downloaded by the user agents....

Components of SMTP

Mail User Agent (MUA): It is a computer application that helps you in sending and retrieving mail. It is responsible for creating email messages for transfer to the mail transfer agent(MTA). Mail Submission Agent (MSA): It is a computer program that receives mail from a Mail User Agent(MUA) and interacts with the Mail Transfer Agent(MTA) for the transfer of the mail. Mail Transfer Agent (MTA): It is software that has the work to transfer mail from one system to another with the help of SMTP. Mail Delivery Agent (MDA): A mail Delivery agent or Local Delivery Agent is basically a system that helps in the delivery of mail to the local system....

Working of SMTP

Below mentioned are the steps of the working of SMTP [Simple Mail Transfer Protocol]....

Some SMTP Commands

HELO: Identifies the client to the server, fully qualified domain name, only sent once per session MAIL: Initiate a message transfer, the fully qualified domain of the originator RCPT: Follows MAIL, identifies an addressee, typically the fully qualified name of the addressee, and for multiple addressees use one RCPT for each addressee DATA: Send data line by line...

Difference Between SMTP and Extended SMTP

Extended SMTP is an extended version of SMTP. Extended SMTP is a set of protocols for sending and receiving electronic messages on the internet. First, Email is sent from sender to sender-server through ESMTP and from sender-server to receiver-server on the internet through ESMTP. ESMTP follows the same protocols as SMTP. It adds more functionality, security, and authentication than SMTP....

Advantages of SMTP

If necessary, the users can have a dedicated server. It allows for bulk mailing. Low cost and wide coverage area. Offer choices for email tracking. Reliable and prompt email delivery....

Disadvantages of SMTP

SMTP’s common port can be blocked by several firewalls. SMTP security is a bigger problem. Its simplicity restricts how useful it can be. Just 7-bit ASCII characters can be used. If a message is longer than a certain length, SMTP servers may reject the entire message. Delivering your message will typically involve additional back-and-forth processing between servers, which will delay sending and raise the likelihood that it won’t be sent....

Frequently Asked Questions on SMTP – FAQs

What is the default port for SMTP?...