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 yahoo.com.
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 freelist.org MX ; <<>> DiG 9.4.1-P1 <<>> freelist.org 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 ;; QUESTION SECTION: ;freelist.org. IN MX ;; ANSWER SECTION: freelist.org. 7200 IN MX 0 dev.null. ;; Query time: 280 msec ;; SERVER: 192.168.1.83#53(192.168.1.83) ;; 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 freelists.org, not freelist.org.
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)