As mentioned in a previous article, email is the electronic way of exchanging (digital) mail through the use of internet and it is the electronic equivalent of the regular mail that we send through a post-office. When you send an email, you send it to a user’s mailbox on a server. But to get clarity on how it actually works, we need to understand certain concepts.
Mail Transfer Agent (MTA)
It is a software that transfers electronic messages from one server to the other. For example, if you are sending an email from [email protected] to [email protected], the message may not be communicated directly between the two servers and it may pass through many other servers while it is under transmission. Let us assume that it passes through Server1 and Server2. Thus, the movement of emails is as follows:
example.com -> Server1 -> Server2 -> thecybercops.net
Each of the servers here has a MTA which deals with this relay of emails to ensure that it reaches it desired recipient. During this relay, the details of each server are appended onto the top of the email header. A header is not a part of the body of the email written by the user, but is rather a part of the technical details appended to the email by the various servers. Thus, every email will always contain a log of all servers it has hopped during its journey.
All this transfer is established by a specialised software called MTA which runs of each of these servers.
Mail Delivery Agent (MDA)
When the email has reached its intended recipient’s server (i.e. MTA of the recipient server), a specialised software called Mail Delivery Agent (MDA) sends it the user’s mailbox. It is the digital equivalent of letter box in the postal system. The user will be able to access and manage the contents of his mailbox. Here, there will be a MDA at thecybercops.net which will deliver emails to the mailbox to the account aman.
Mail User Agent (MUA)
A Mail User Agent (MUA) or an email client (e.g. Mozilla Thunderbird, Mutt) is a software which allows a user to access and manage his email mailbox. It will generally display the contents of the mailbox in a graphical (Mozilla Thunderbird) or textual manner (Mutt).
For Wikipedia entry on Mail Transfer Agent, click here.
For Wikipedia entry on Mail Delivery Agent, click here.
For Wikipedia entry on Email Client (Mail User Agent), click here.
For more posts on Email, click here.
For more posts in The Cyber Cops project, click here.