SMTP is an abbreviation for Simple Mail Transfer Protocol. It is the process of exchanging and delivering emails through IPs. The sending and delivery of emails undergo a process that is quite similar or even the same with the process of sending mails through the traditional post office. In the traditional mail process, the envelop you send is handled by an organized system and passes through a number of steps before it is delivered to the recipient. But unlike the traditional mail process, the role of the postman in the email process is played by a computer running SMTP. Once you send out your email to a friend, the email you send out is picked up and moved to this server which will send the emails to the receiver. In other words, the email process involves a conversation between two SMPT servers, namely, the outgoing SMTP and the recipient’s incoming server. There are special websites like spammer where you can know more about it. Below is the process of email delivery via SMTP.
1. The process starts when you use your email address to send out an email with your webmail or mail client to another email address. Your mail client or webmail is known as the acronym for message user agent. The email is delivered to a SMTP server of your client through port 25. Once you create your email address, your client is given a server which plays the role of a Message Transfer Agent abbreviated as MTA. Your clients engage the server in a brief conversation where all the data concerning the transmission of the message (sender, recipient, domains and others) are checked by the server. Bear in mind that SMTP language defines only the transmission of the message. It does not handle the content of the message.
2. The email is immediately delivered to the recipient’s account if the domain where he or she has his or her account is connected directly to the server. However, in situations where it is not connected to the server, the message will be relayed (the technical words for sending out of the email) by the SMTP to another incoming server closer to the recipient which will receive and store the email.
3. In case the server of the recipient is busy or down, the message will be dropped to a backup server by the SMTP. In situation where none of the servers is available or where both servers are busy, the email will be put in queue and the delivery will be periodically retried. If delivery is not successful after some periods of retrial, the email will be relayed back to the sender as failed delivery.
The final stage of email delivery via SMTP is handled by POP if there are no issues. POP is another protocol that collects emails from the receiving server and delivers it into the inbox of the recipient.
Note that the SMTP servers that are utilized when you email another person is shared among users and they do not use dedicated IPs. The implication of this is it is possible for one to end up making use of the IP utilized by a spammer. If this occurs, the correct delivery of your email could be affected by this.