{"id":378,"date":"2011-12-16T22:14:44","date_gmt":"2011-12-16T22:14:44","guid":{"rendered":"http:\/\/microsoftgeek.com\/?p=378"},"modified":"2011-12-16T22:16:01","modified_gmt":"2011-12-16T22:16:01","slug":"how-does-email-work","status":"publish","type":"post","link":"https:\/\/microsoftgeek.com\/?p=378","title":{"rendered":"How Does Email Work?"},"content":{"rendered":"

\"\"<\/p>\n

You send and receive it everyday, it\u2019s instantaneous, and it doesn\u2019t cost a thing. It\u2019s email, one of the most important tools of today. Let\u2019s take a look at how it works, under-the-hood and in normal language.<\/p>\n

What Exactly Is Email?<\/h3>\n

Electronic mail (abbreviated as e-mail, email, E-Mail, etc.) is a very old form of computer-based communication. A long time ago \u2013 in technological, not human, terms \u2013 computers were giant machines. People used dial-up terminals to access them, and each machine held storage for multiple users. As is the case with any community, people found useful and unique ways to communicate with one another, and a messaging system evolved. The caveat was that you could only send messages to other users on the same system, at least up until 1971. As the story goes, along came Ray Tomlinson who sent the first email by addressing a user on another system using the \u2018@\u2019 symbol. Obviously, both the underlying dynamics and far-reaching consequences weren\u2019t so simple, but it was that notion that brings us to where we are today.<\/p>\n

\"terminal\"<\/p>\n

(Image from ajmexico<\/a>)<\/p>\n

Email was, at that time, the equivalent of today\u2019s text message. Over time, it changed and evolved like anything else; it has sender and receiver info, a subject line, a message body, and attachments, but on the whole, emails are pretty simple documents. It\u2019s not so easy to get it from point A to point B, however. Like anything else, there\u2019s an intricate process involved that works behind the scenes to make it seem as seamless as possible. A lot of the ideas used in relaying email were important in formulating document transfer, which is at the core of things like bulletin board systems and the world wide web.<\/p>\n

From Sender to Recipient<\/h3>\n

Let\u2019s start with an illustration of the process. It may not make complete sense at first, but it\u2019ll be useful to refer back to.<\/p>\n

\"Email<\/p>\n

When someone, let\u2019s say a spice seller, sends an email, it has to have an address in the form of user@domain.ext. Our example has freman.alpha@arrakis.com. The email gets sent by the client to an outgoing mail server via Simple Mail Transfer Protocol. The SMTP server is like your local post office, which checks your postage and address and figures out where to send your mail. It doesn\u2019t understand domains, though. They\u2019re a sort of abstract thing, so the SMTP server contacts a Domain Name System server. The DNS server is a sort of phone or address book for the internet; it translates domains like \u201carrakis.com\u201d to an IP address like \u201c74.238.23.45.\u201d Then, it finds out if that domain has any \u201cMX\u201d or mail exchange servers on it and makes a note of it. This is like your post office consulting maps of where your mail is supposed to go, calling their local post office, and checking to see if your friend has a mailbox or P.O. box to receive mail.<\/p>\n

Now that the SMTP server has the proper info, the message gets sent from that server to the target domain\u2019s mail exchange server. This server is referred to as an MTA, or Mail Transfer Agent. It decides where exactly to put the mail, much like how your friend\u2019s post office figures out how best to get it delivered. Then, your friend goes and fetches the mail, usually using a client that works via POP or IMAP.<\/p>\n

POP vs. IMAP<\/h3>\n

\"pop<\/p>\n

These two acronyms plague email settings panels everywhere, so let\u2019s take a deeper look at them. POP stands for Post Office Protocol. It\u2019s useful because, like a post office, you can pop in, grab all of your mail, and then leave. You don\u2019t need to stay connected, and aside from leaving a copy on the server, it\u2019s a pretty cut-and-dry procedure. If you don\u2019t leave a copy on the server, it doesn\u2019t require much space or bandwidth either. You can use POP to grab mail from several different inboxes on several different email servers and consolidate them on one.<\/p>\n

It has its drawbacks, though. POP is a unidirectional protocol; information travels one way. Once you download the email to a client, it\u2019s up to the client to sort through its different statuses and so on. That\u2019s fine if you only ever access mail from one place. Nowadays, though, it\u2019s common to get email access from your phone\u2019s client, the web interface when you\u2019re away somewhere, and a client when you\u2019re at home. It\u2019d be tedious to sort through all of that info over several devices, assuming you\u2019ve even kept a copy of each email on the server to begin with.<\/p>\n

\"imap_pop\"<\/p>\n

(Image from SuccessByDesigns<\/a>)<\/p>\n

IMAP\u2019s a bit smarter about things. While POP can be considered to be very \u201cclient-oriented,\u201d the Internet Message Access Protocol was designed to work in a different way: it\u2019s \u201cserver-oriented,\u201d and bi-directional. Clients have a two-way communication with their servers. All messages are kept on the server so multiple clients can access them. When you check an email on your phone, it\u2019s marked as read and during the next interaction with the server, that status is sent back so all other clients can be updated with it. It\u2019s like having your mail sent to an assistant at the post office who categorizes it and stores it for you, gives it to you whether you\u2019re at home, at work, or actually there, and makes changes to the stored copies as you do.<\/p>\n

You can keep a properly marked archive on your home client as well as on your mail server. IMAP also supports an offline mode; changes are synched with the server the next time you\u2019re online. You can configure IMAP mail servers to fetch mail from POP inboxes, too, which works really well if you\u2019re looking to consolidate. Of course, since IMAP works with the \u201ccloud\u201d ideal, server access and storage can be issues. Thankfully, storage space and bandwidth isn\u2019t as expensive as it used to be, but this can definitely be a trade-off for some people.<\/p>\n

Both SMTP and MTA<\/h3>\n

Unlike your physical mailbox, your outgoing and incoming mail are handled by two different types of servers. There\u2019s really no discrimination towards receiving servers; any computer can be made an MTA pretty easily and handle things well. Sending mail is a different story. SMTP servers must have static IP addresses, and most ISPs block port 25 so that their users can\u2019t send mail themselves. Why? Because of the massive amounts of spam gnawing away at our collective bandwidth, the very stuff your MTA should be configured to filter out. You can configure your clients to use your ISP\u2019s SMTP server in lieu of running your own. The point is that you need both an MTA and an SMTP server to use email, as each is specialized for what it does.<\/p>\n

\n

Email\u2019s an important part of our everyday lives, but it\u2019s nice to understand just how it works. After all, we wouldn\u2019t have the internet without it.<\/p>\n","protected":false},"excerpt":{"rendered":"

You send and receive it everyday, it\u2019s instantaneous, and it doesn\u2019t cost a thing. It\u2019s email, one of the most important tools of today. Let\u2019s take a look at how it works, under-the-hood and in normal language. What Exactly Is Email? Electronic mail (abbreviated as e-mail, email, E-Mail, etc.) is a very old form of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-378","post","type-post","status-publish","format-standard","hentry","category-computer-tech-stuff"],"_links":{"self":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/378","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=378"}],"version-history":[{"count":3,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/378\/revisions"}],"predecessor-version":[{"id":380,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/378\/revisions\/380"}],"wp:attachment":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=378"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=378"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=378"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}