Simple Mail Transfer Protocol ( SMTP )
SMTP is a protocol of application layer in TCP/IP model.
It handles sending electronic mail between the servers and operates on the port 25 of TC by default.
It uses email addresses to send the mails to the target address.
SMTP allows sending various kinds of messages such as :
- Single message to a single recipient.
Single message to multiple recipients.
Along with text messages it also allows images, video and audio format also .
This protocol can also handle some errors of its own such as incorrect email address.
FORMAT OF THE MESSAGE
The message to be sent consists of two parts:
Header consist of all the authorization information such as sender address, receiver address and subject of the mail.
Body stores the message that need to be sent along with the attachments like images, videos etc.
Mails are sent via the SMTP service on the web and retrieved by the IMAP/POP3 on the receiver side.