How Mail System Work
A mail system consists of many parts. There are plenty of servers that are needed to make it all happen, and the end users needs clients to take advantage of the services provided by the servers.
First of all, a mail man who can carry the mail to the post office is needed. That’s called a Mail Transfer Agent (MTA). The MTA only knows one language when talking to other MTAs and other system parts: the Simple Mail Transfer Protocol (SMTP).
At the post office, the mail can be filtered to prevent you from receiving spam, viruses and then put in the right mailbox. This post office is called Mail Delivery Agent (MDA). The MDA might also be able to send out auto respond messages (sometimes called vacation messages). In some post offices, every user can have a number of mailboxes. These mailboxes are often called “folders” by the end users, but in reality they are a collection of mailboxes.
Now you can walk to the post office and read your mail, but since this is the Internet you don’t actually have to go to the post office. Enter the Mail User Agent (MUA), often called a mail client. This wonderful piece of software makes it possible to read the mail at the post office without having you walking over there. It’s like the post office had a camera and you a TV set. When the post office clerk holds your mail up in front of the camera, you can read it while sitting in your TV sofa. The mail never leaves the post office, but you can read it all the same! The language you use to tell the post office clerk which mail to show you, and where to put it after you read it is called Internet Message Access Protocol (IMAP) and the post office clerk showing you your mails is called IMAP server. IMAP is great; since it lets you read your mail wherever you are. All you need is your TV – sorry, I mean MUA. And don’t worry about not being able to speak IMAP yourself – your MUA will help you with it.
There are also simpler post offices which can’t handle the remote reading feature. Those post offices only let you get your mail and store it in your home. The MUA will act as your servant, getting your mail for you and putting it in your home. The language used when your MUA speaks to the post office to get your mail is called Post Office Protocol (POP).
But sometimes you want to write mails as well, and when they are written they need to be delivered. Who will take care of that? The easy way is to let your MUA talk to a Mail Submission Agent (MSA). The MSA will take the mail and hand it over to the MTA, who will then deliver it to a post office.
If you have a mail system, you most likely have users with mail addresses. Those users and addresses are defined in a user database, which is accessible by all other system part for verification purposes.
there are six different parts in a mail system: the MTA, the MDA, the MUA, the MSA, the IMAP and/or POP server, and the user database. All six parts have to be there to have a complete mail system, but all six parts don’t have to be different pieces of software. Some software solves more than one task. The MTA and MSA can be integrated into the same piece of software for instance.
First of all, a mail man who can carry the mail to the post office is needed. That’s called a Mail Transfer Agent (MTA). The MTA only knows one language when talking to other MTAs and other system parts: the Simple Mail Transfer Protocol (SMTP).
At the post office, the mail can be filtered to prevent you from receiving spam, viruses and then put in the right mailbox. This post office is called Mail Delivery Agent (MDA). The MDA might also be able to send out auto respond messages (sometimes called vacation messages). In some post offices, every user can have a number of mailboxes. These mailboxes are often called “folders” by the end users, but in reality they are a collection of mailboxes.
Now you can walk to the post office and read your mail, but since this is the Internet you don’t actually have to go to the post office. Enter the Mail User Agent (MUA), often called a mail client. This wonderful piece of software makes it possible to read the mail at the post office without having you walking over there. It’s like the post office had a camera and you a TV set. When the post office clerk holds your mail up in front of the camera, you can read it while sitting in your TV sofa. The mail never leaves the post office, but you can read it all the same! The language you use to tell the post office clerk which mail to show you, and where to put it after you read it is called Internet Message Access Protocol (IMAP) and the post office clerk showing you your mails is called IMAP server. IMAP is great; since it lets you read your mail wherever you are. All you need is your TV – sorry, I mean MUA. And don’t worry about not being able to speak IMAP yourself – your MUA will help you with it.
There are also simpler post offices which can’t handle the remote reading feature. Those post offices only let you get your mail and store it in your home. The MUA will act as your servant, getting your mail for you and putting it in your home. The language used when your MUA speaks to the post office to get your mail is called Post Office Protocol (POP).
But sometimes you want to write mails as well, and when they are written they need to be delivered. Who will take care of that? The easy way is to let your MUA talk to a Mail Submission Agent (MSA). The MSA will take the mail and hand it over to the MTA, who will then deliver it to a post office.
If you have a mail system, you most likely have users with mail addresses. Those users and addresses are defined in a user database, which is accessible by all other system part for verification purposes.
there are six different parts in a mail system: the MTA, the MDA, the MUA, the MSA, the IMAP and/or POP server, and the user database. All six parts have to be there to have a complete mail system, but all six parts don’t have to be different pieces of software. Some software solves more than one task. The MTA and MSA can be integrated into the same piece of software for instance.
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