Software

Why you can't send an e-mail more than 500 miles

There's nothing worse than a user who reports a problem to his helpdesk along with a "description" of the cause--"description" here being a stand-in for "insane supposition that flies in the face of all logic and physics." This story reminds you that sometimes the insane user theory is correct: "We can't send [e-mail] more than 500 miles." It's totally true.

There's nothing worse than a user who reports a problem to his helpdesk along with a "description" of the cause--"description" here being a stand-in for "insane supposition that flies in the face of all logic and physics." This story reminds you that sometimes the insane user theory is correct: "We can't send [e-mail] more than 500 miles." It's totally true.

The details are actually rather involved and cite some specific quirks to Sendmail and SunOS--admins of both are encouraged to read the full recounting--but it breaks down to something like this:

A tech at a research university gets a call from the Chairman of the Statistics Department, who has noted that he can't send email to anyone more than 500 miles away. The tech is incredulous, but the story checks out: He, too, can send an e-mail to anyone within a rough 500-mile radius of campus, but not anywhere outside. Strange as it sounds, the insane user theory was correct...mostly.

Turns out, the tech couldn't reach anyone closer than 500 miles if the recipient's ISP was more than 500 miles away. Impossibly, physical distance had become a limiting factor, arbitrarily cutting off at about 500 miles.

A rare confluence of events lined up to make this happen. In a nutshell, the mail server had been reset to accept zero timeouts on connecting to a remote SMTP server. The university network was also 100 percent switched, so the mail server wouldn't have encountered a timeout of any kind until it hit the receiving mail server. The 500-mile limit was dictated by the speed of electrical transmission between the campus server and the receiving server.

A timeout of zero in Sendmail works out to about 3 milliseconds. Three light-milliseconds is about 558 miles, with a little less for electrical resistance in the line. Anything further away would timeout. Once the tech reset the default timeout, everything was fixed.

Insane, but true. Don't be so quick to discount those crazy user theories next time.

(Found via reddit.)

About

Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

15 comments
Deadly Ernest
Deadly Ernest

The best I came across was a computer that automatically reset when you flushed the toilet. The user even demonstrated it to four techs before I was sent out. Being a bit more used to non center of the city living I looked at the house's utilities as it was on the edge of the city. Sure enough, right on the end of the power line and beyond the town water supply. Worked it out yet. Every time you flushed the toilet it refilled the cistern. This caused the water pump to kick in to pump water from the dam. This resulted in a drop in power causing a brown out, computer reset. A cheap Uninterruptable Power Supply and computer problem solved as the battery handled the line drop for the few seconds needed. You never can tell how life will bite you.

Oz_Media
Oz_Media

Headwrecker, I'd have loved to get that one. You could piss away weeks working on it and kill all kinds of time while seemingly looking busy and important. What a hoot!

richy.mitchell
richy.mitchell

Once told a user to right-click in the box and then asked what the menu said....It says 'Click', I wrote it in the box....Do you have an Apple computer?

Altotus
Altotus

Unintended consequence. A single setting in a complex system.

Chaosmstr
Chaosmstr

Every time he flushed his toilet, his computer would reboot. Turns out he had his own well, and the pump would brown out his house when it kicked on. But we had a hell of a time diagnosing the problem!

CavalierX
CavalierX

One of the best calls I ever had when working a helpdesk "back in the day" was from a user whose monitor was flickering. She told me with utter seriousness that she felt the problem was cause by "the light bulb behind the screen." I duly noted the user's explanation of the problem in the ticket. The next day, I arrived to find a small light bulb on my desk courtesy of hardware support, with a tiny taped-on GE logo and the words "monitor bulb." Never laughed so hard in my life.

Tearat
Tearat

The look on the face of the tech must have been priceless Very funny Thanks for the laugh Does anyone else have any of these types of storeys? Please share we all need a laugh to help us with the impossible people we deal with Steve

cwmcclure
cwmcclure

Before the days of personal computers anomalous situations were encountered by knowledgeable persons but some problems baffle everyone. I have heard the following repeated by many persons who had to trouble-shoot big systems. Years ago a large computer installation was plagued by mysterious errors and erratic behavior. After having tens (or maybe hundreds) of CNR (Can Not Reproduce) trouble reports, the application software (and finally the operating system) were instrumented to report on various error indications. After finding no recognizable software problems, hardware monitoring revealed a lot of hash (electrical noise) on critical circuits whenever the software found malfunctions. Careful analysis of the now documented (but rather infrequent) errors showed that while the exact time of the errors was unpredictable, the problems occurred only during the day shift on weekdays -- and only when the weather was bad. A noise alarm sufficient to "wake the dead" was wired to go off whenever strange signals were detected; customer engineers were assigned to prowl around the computer (drinking coffee and reading the newspaper) whenever the weather forecasts indicated bad weather. On a particularly rainy day a technician was going to his car (which he had parked in the back lot because the front lot was full) when the alarm went off just as he opened the door to the loading dock (the most convenient path to the back of the building from the computer room). The technician's head jerked upright and he realized that he could see out the big open loading doors at the rear of the building and across the adjoining field he could see a big aircraft approach radar antenna associated with the nearby airport. Immediate discussions with the airport management determined that this radar was used only when bad weather necessitated the use of an alternate runway. The loading dock was open only during the day and only during weekdays. A few quick tests showed that the radar signal was attenuated by the loading dock doors and by the steel walls of the building -- EXCEPT when the rarely used access door was open. Permanently sealing the door eliminated the malfunctions. Moral of the story -- believe the reports and examine the total environment.

nfhiggs
nfhiggs

I recall the story of the woman that claimed her dog was able to predict when the phone was going to ring by barking and howling. This was the 'old style' phone system from the 70's. Turned out the phone line was not properly grounded and the ground path for the 70 volt ringer signal went through a metal pole that the dog was chained to. Every time an incoming call came the dog got shocked, started howling and peeing everywhere. The ground path was not good enough to allow the ringer bell to function until the urine soaked the ground near the pole, allowing the ringer bell to work.

brian.mills
brian.mills

It's rather appropriate that the pump would cause a "brown out" when flushing the toilet! In all seriousness, I guess the solution to that would be connecting a UPS to the computer.

michaellashinsky
michaellashinsky

That wasn't a monitor. That was a light-Brite. (That's an old toy for you kids.)

blacksmith
blacksmith

I've been doing computer support since the early '80's, when I was in the Army. The Army equivalent of the ID10T error was OHS -- operator head space. I found a BUNCH of good stuff at this site: http://rinkworks.com/stupid/

robo_dev
robo_dev

Years ago, an old PC would not read it's floppy drive and would not boot. You old-timers will recall the full-height 5.25" floppy drives on the original PC. Inside the PC was mouse fur, droppings, and popcorn kernels. The mouse had chewed through part of the ribbon cable for the disk drive. The mouse was not found inside the PC and ironically, this was before computers had mice, the pointing device, that is.

robo_dev
robo_dev

Symptom: PC seemed to be rebooting for no reason.....She was the Executive assistant to the president of the company, and had a company PC at home. After making a special house-call and testing everything, as we walked out of her home office, she flipped off the light switch and I noticed that the PC switched off. Another executive assistant tried to print an address on an envelope using her laser printer. A CLASP envelope. Needless to say, the clasp wore a distinct groove in the fuser roller of the printer, leading to black stripes being printed on all output. Funniest environment I ever visited was a PC used in the production environment of a 'Graphite Milling Factory'. EVERY item in that office was covered with smears of graphite...floors, desks, keyboards, etc. The power supply had failed on the PC (surprise). (Graphite is conductive). The guy there told me that they take apart and blow the graphite out of the PCs about once a month. Other random bits: At a government site, hard drives were not allowed to be in the PCs, nor was any media allowed to leave the facility. It cost more to 'custom order' Compaq PCs without drives. So the first order of business while installing 20 brand new PCs was to remove the hard drives and put them in the shred bins.