The DNS (Domain Name System) is a conversion tool that allows you to associate an IP address, consisting of digits, with a domain name, that is, a series of letters, often chosen to form recognizable words. In the case of Internet sites, the domain name is similar to the Web address. The DNS is a system absolutely necessary for the usage of a SMTP Server .
Each device connected to the Internet (or to a local network) has an IP address that allows to recognize it. However, the form of this IP is complex: a series of numbers, sometimes accompanied by letters, which do not present a particular logic in the eyes of the user.
In order not to get lost, an elegant solution was found: to associate with the addresses a clearer and concise name, composed of letters and called domain name. For example, IP 220.127.116.11 corresponds to the word "en.mailpro.com", which is much simpler to remember.
The DNS allows to list these associations. It is a sort of system of "white pages" that gives the possibility to find a domain name starting from an address, or the reverse. Each time a server sends a request, it passes through this step, known as resolution.
Email addresses also have a domain name: the part behind the 'at sign' (for example, mailpro.com). In addition, email addresses are recognized by the MX code in the DNS syntax. This means that when sending emails, the SMTP server that is looking in the DNS directory must first consider MX-stamped domain names. This precaution ensures that the message is transferred to an email box.