The case of the 500-mile email

[jmtame]

And I was fairly certain I hadn't enabled the "FAIL_MAIL_OVER_500_MILES" option.

That would be a great feature to have as part of a "new admin initialization" program or something :D

[sidsavara]

An old story but one of my favorites =)

[_hgt1]

The case of the 500-year anecdote.

[light3]

I thought it was a made up story till i got to the end O.o

[mqt]

"Have you run tcpdump or strace?"

If you're curious about where to start debugging, this blog post gives a good rundown:

http://sysadvent.blogspot.com/2008/12/sysadmin-advent-day-1....

[petercooper]

Oldie but a goodie. Highly recommend reading this but if you don't want to..

SPOILER - though you should be reading the article first anyway if you care!

An accidental downgrade of Sendmail made Sendmail have a zero second timeout on sending mail that ultimately worked out at 3 milliseconds, just enough to hit servers within a certain radius..

I bet there are several pieces of software that could have a zero timeout triggered in a similar way. The difficulty of figuring it out? About the same as with this guy ;-)

[kajecounterhack]

Yeah it's old but I never did figure out how his geostatisticians knew how to see if the email went further than 500 miles...I mean, that'd mean they know to measure where the mail servers are rather than the actual user, right? oh well.

[IsaacSchlueter]

Back then, most of the users were probably within a local telephone call of their mail server.

[SlowOnTheUptake]

I'm a little unclear on one point: knowing that 3ms * 186000 miles/sec is roughly 550 miles, wouldn't the radius be ~275 miles? (Round trip travel time before timeout)

That is assuming that packets could actually travel that fast through a wire.

[13ren]

my shell doesn't have "units": http://www.google.com/search?q=.003+lightseconds+in+miles

[mqt]

units isn't a shell function; it's a program that's a standard part of Unix. You can install GNU Units on Linux.

It even lets you define your own units in units.dat. Pretty cool.

http://en.wikipedia.org/wiki/Units_(Unix)

[nazgulnarsil]

why did he freakout? surely the idea of distance = ping time and there being some sort of timeout going on is one of the simplest explanations?

[donw]

You're obviously not a sysadmin, living on the front line between the non-technical, and mountains of computer hardware. I've worked at more than a few places where "I can't send an email more than 500 miles." translates to "One person 500 miles away has had their automatic spam filter nab my message."

I'm much more inclined to believe user error first. That said, the words "consultant" and "upgrade" give me cold chills...