eli5: How exactly are emails sent, like the actual process of the data getting sent to another device that’s for example on another continent?
In: Technology
Hi 🙂
How Eli5 would you like it? 😉
– E-Mails aren’t getting sent from your outbox to someone’s inbox,
– but rather over your internet provider’s connection
– to your email service,
– over their internet through different connections across the globe,
– to the recipient’s server…
– Where it waits to be downloaded (Either until they check or sending out a “Hey, you have new mail” to their client).
Let’s say your mailbox is mysupergreatmailbox444 at Hotmail.com.
and you send a message to Germany, e.g. ilovetogetmailsfromoverseas222 at GMX.de.
– You write the E-Mail and hit send.
– If you use an email client, there will be settings like server, port, account password, and so on.
– Internet & Computers doesn’t work with names like “Hotmail” or “GMX”, but with IP addresses (numbers like 123.222.127.333 or a more modern format).
– Your computer asks your internet provider or other “DNS” (Domain name service, basically a phone book) what IP address (a number) Hotmail.com has.
– Then your e-Mail client will connect to that server’s number with your log-in data, trying to establish a connection.
(If you write an email on your email provider’s site, that step basically gets skipped. You instead log in to the website and save the email there directly.)
– Hotmail then saves your mail to your account’s outbox, sends it to the receiver. If it fails it will retry a couple of times.
– Similar process. Hotmail asks a DNS what IP-Address GMX.de has. Then tries to send the data over the internet tubes to that server’s IP.
– Each transfer is made up from different little pieces of information, and gets collected at the other end. So your eMail might get send in little chunks across different routes, servers, across sub sea cables, ground lines, satellite. Imagine you write a 10 page letter and send each page through a random postal service. The recipient sorts them if they arrive out of order. If a page goes missing, the recipient will ask for it again. It’s rather chaotic 🙂
– The recipient’s mail client will check their provider’s (GMX in the example) server—
– You’ve guessed it. The E-Mail client will look up GMX’s IP address, connect with log-in data. Send and download messages.
– The recipient’s E-Mail program uses either a protocol like IMAP (TL;DR: Synchronizes new messages with the server and your other devices) or the older POP3 protocol (Basically downloads and deletes).
– The E-Mail client will download & display the message. If they use their E-Mail provider’s website, they will display the mails as website to look at and thus provide a human interface to the saved E-Mails.
Never have the recipient’s E-Mail program and yours interacted directly. Not unlike regular mail.
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