Simple Mail Transfer Protocol (SMTP) is the routing by which emails cross the Internet. As the name implies, it is a simple routing system in which the sender and the recipient of a message are specified. A verification is then made on the existence of the two people, then the body of the email is sent to its destination.
When sending an email, it is routed from server to server until it reaches the inbox of the recipient.
An SMTP platform is a remote computer that the customer contacts in order to transmit their emails. For most Internet users, it is the ISP that owns it: when a user clicks on the send button of a message, it actually makes the request to the SMTP server of its host, To carry the email to its recipient.
In order to remain certain of its proper functioning, it is possible to test it using the "telnet" command on the port 25 of a remote platform. This protocol requires textual instructions.
It runs in connected mode, encapsulated in a TCP / IP frame for data transfer, directly to the recipient's mail server.
Each message is sent to mail servers, which are responsible of the transportation (named Mail Transport Agent, or MTA). It will pass through several of these agents, until reaching that of the recipient. They communicate with one another through the SMTP protocol, which is why they are also called "SMTP servers".
When an Internet user receives an email, his MTA delivers it to the MDA server, or Mail Delivery Agent, which handles the delivery of the incoming e-mail in the mailboxes. It stores the email, until the user comes to collect it.
Two types of SMTP platforms can be chosen for their emailing routing, each presenting advantages and disadvantages: these are dedicated and shared hosting.
SMTP Servers Dedicated Servers are, as their name indicates, devoted to one user only. Each of them, represented by one or more remote machines, is entirely the responsibility of the customer: the client is free to administer their computer operations as desired, with their applications, operating systems, security protocols, etc.
Unlike dedicated hosting, the shared server is shared among several clients, all of which have the same IP address. Less costly, it leaves less freedom to users and offers less bandwidth and disk space, but is free from the responsibilities of management of the system, since the host remains in charge of its technical aspect: its administration, its Security updates, etc.