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Sunday, April 13, 2008

One letter, big difference

I was trying to send a mail to the DokuWiki development list for a couple of days with regards to a possible problem in their mailing-code and my mail seemed to go in a black hole. I started to have conspiracy theories: my e-mail address was banned. Yahoo was banned. The end is near. Finally Yahoo was kind enough to give a delivery failure notice stating that:

Hi. This is the qmail-send program at
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

Sorry, I couldn't find a mail exchanger or IP address. (#5.4.4)

Do you see my error yet? Right, I didn't either. So I opened up a console and typed:

$ dig MX

; <<>> DiG 9.4.1-P1 <<>> MX
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29460
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;                  IN      MX

;; ANSWER SECTION:           7200    IN      MX      0 dev.null.

;; Query time: 280 msec
;; WHEN: Sun Apr 13 23:26:59 2008
;; MSG SIZE  rcvd: 54

At this point I was convinced that their mail server is down. However this explanation didn't seem right, since I received e-mail regularly from the list even in the last couple of days. Finally it hit me:

The address of the mailing list is, not

A couple of conclusions: Always double check your assumptions. Assume that you're wrong (80% of the time you will be right - then again 58% of the statistics is made up on the spot :-)). Rely on your computer to prefill as much information in e-mails (and other communication media) as possible. This also shows why typo squatting is such a lucrative business. And if you are a business, try to anticipate such incidents and buy the given domain names if available. Consumers will thank you! (or more probably: they will never notice, but at least they will find you)


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