‘You try not to be cynical, but without the distraction of Iraq [people would notice] that the economy is doing poorly, and the old-fashioned Republican tax cuts for the folks that are doin’ well will seriously curtail services for people who are struggling out there. I don’t think that’s the kind of country Americans really want.’ – Bruce Springsteen interviewed in the February 28 Entertainment Weekly

‘The statistics on sanity are that one out of every four Americans is suffering from some form of mental illness. Think of your three best friends. If they’re okay, then it’s you.’ – Rita Mae Brown (as quoted at the end of our condo newsletter)

And now . . .

. . . at long last . . .

. . . Where DO e-mails go?

[Warning: Curiosity may not have killed the cat but merely put him to sleep. Feel free to stick with the Springsteen interview.]

John Kasley asked this question February 24: ‘I occasionally send myself an e-mail with a URL in it, as a reference to something I may want to investigate later. I just sent myself such a note, and it took 9 minutes to get back here. I’m on a cable connection. Where did the message go and what did it do? I hope it had a good time. Your readers seem to know everything in the world. One of them will surely know this.’

John Seiffer: ‘Emails (like everything on the web) exist on a computer somewhere called a server. When you send an email, your computer sends it to the server you’re connected to – owned by the place you get your internet account from, called your ISP, Internet Service Provider. That server then checks the address of where it’s going to and sends it out to the server that handles that address. Then, to receive email, your computer gets it from that server. It’s likely that – even sending to yourself – the ‘sending server’ and the ‘receiving server’ are not the same. It as if there were one mail carrier who picked up mail you sent and another who brought mail you received. It’s possible that in sending from one server to another, the message got delayed and parts of it had to get sent again till the whole thing got there. It’s also likely that when the message got to one or the other server it just waited in line for a while before it got sent out or before it got filed in the right place so some other software would know it was there (AOL used to be notorious for this). And it’s also possible that a person’s computer is only set to check for new emails every 10 minutes (mine is actually set to check every 30). This is something you can usually adjust in your email program.’

Peter Ludemann: ‘There’s a long answer, involving jargon such as SMTP, POP3, IMAP4, MTAs, etc. I’ll try a shorter answer. The Internet mail system was designed in the early 1980s. In those days, always-on connections were an unheard-of luxury. So, mail was sent by ‘store-and-foreward,’ which means that it would be relayed from one machine to another until it reached its destination (similar to how the real post-office sends mail between offices). Each relay would keep trying at intervals to connect to the next machine, until it finally had sent the message. Even the most trivial mail message requires:

1. send from your machine to your mail server
2. send from the mail server to the recipient’s mail server
3. send to the final destination machine.

‘This is necessary because otherwise both you and the recipient would have to be connected at the same time to send mail (as in Instant Messenger). In the case of sending mail to yourself, step #2 can be left out, but you still have an intermediate mail server. In some cases, there might be multiple intermediate servers (often called “gateways”).

‘There can be any number of reasons why things get delayed on a server … can’t connect from your machine to the server, the server is busy, it’s out of disk space and needs to wait for some mail to be delivered before accepting yours, etc., etc. (Even today this relaying occasionally fails and you get a message saying that the server tried for 3 days and couldn’t deliver the message.)

‘In the early 80s, if a message was delivered within half an hour, you were usually very happy. Often the mail didn’t get delivered at all and you got no notification of the failure. Nowadays, people assume that email is reliable and are amazed when it takes more than a few seconds to arrive.’

Erik Streed: ‘When you send an email from a program like Outlook or Eudora it typically contacts your mail server (something like pop3.mit.edu or mail.mit.edu in my case) and passes on the message. That server then looks at the To:, CC: and BCC: fields and figures out which other servers it needs to contact to pass the message along. It might also check for viruses, tack on some good legal voodoo disclaimer or toss back the message if it’s too big.

‘One of the more common rules of the system is . . . to wait. There are two reasons for this. One is that if the server accumulates several messages going to the same place (say aol.com) it can talk to that server once and everything is much more efficient. It’s kinda an artifact from when the ‘net was very young and your mail server might make a mail run once a day or once an hour by directly calling someone else on a modem. The other reason is bugs. Suppose you have a mailing list program. You send a message to the list address and the program emails everyone on that list. If someone’s email has turned sour and the message bounces, the entire list could be mailed (instead of just the sender). Most list servers are smart enough to figure this out (now, at least), but by delaying a message for a few minutes can change a devastating bug (or virus for that matter) into a minor nuisance.’

Turner Jones: ‘POP servers (Post Office Protocol) are busy, busy little bees. Every ISP (internet service provider) has to have one so that you can get your e-mail. These little bees are constantly opening the door, getting the mail, sorting and stacking, moving and storing, and opening the door again and sending the mail out. All day long. It gets to be too much some times and to top it off, some bees are smaller and weaker than other bees so they can’t do as much work as the bee keeper (ISP) would like them to. In fact, some bee keepers are just downright cheap and don’t really care how overworked the bees are. If you are interested, here is an informative link – hopefully, without the bee analogy.’

Brad Hurley: ‘Where do e-mails go? Answer: When you click SEND your e-mail gets chopped into pieces (called packets), which are then volleyed about from server to server until they reach their intended destination, where they are magically reassembled. Usually that process takes milliseconds, but sometimes things get held up. Traceroute, a command built into both the Windows and the Mac operating systems, lets you to see how many bounces it will take for a request from your computer to reach a specified server. It also shows you how long the request takes to get there. Instructions for Windows are here. For Mac OSX, here.’


Comments are closed.