Archive for the ‘Compumataters’ Category

550-5.7.1 errors from Gmail

email-43107-344170_478x359If your mail bounces from Gmail with the following message:

host[2a00:1450:400c:c02::1b] said: 550-5.7.1 [abcd:ef01:23:45:67:8:9abc:def0] Our system has detected that this
550-5.7.1 message does not meet IPv6 sending guidelines regarding PTR records 550-5.7.1 and authentication. Please review 550-5.7.1 for more 550-5.7.1 information. u5si1912210wyu.71 - gsmtp (in reply to end of DATA

you’re probably using Postfix with IPv6 turned on. To fix this, tell Postfix to just use IPv4. In /etc/postfix/, change

inet_protocols = all


inet_protocols = ipv4

If it’s missing, just add the latter line. Restart postfix and hoppla! Es klingelt.

Gmail also wants a proper PTR (reverse IP lookup) record for the mail server, but the error message is probably something different (or nonexistent) if that’s missing.

In Pursuit of Higher Knowledge


Once upon a time, before the invention of the wheel, I applied for a job at IRCAM in Paris. I was told in the phone interview they were down to two candidates. Alas, it wasn’t meant to be, which in turn meant I never got business cards with the coolest office address in the entire universe: 1, place Igor Stravinsky, 75004 Paris.

This May my dear friend, Belgian composer extraordinaire Daniel Schell, myself, and our esteemed colleague Thomas Pintelon (who also happens to be Daniel’s son-in-law) will be presenting our work on “the optimal connection of chords”, which features heavily in Daniel’s compositional work, at IRCAM. The date is 24th May, the time is 2.30pm, and the address is as stated above. If you’re in the neighbourhood, do drop by, it’s free entry, and if you mention this blog post I will shout you a beer afterwards. There’s a short blurb in French on IRCAM’s pages. (Edit 2013-11-09: The whole presentation was caught on video! I had no idea.)


If you are in Espoo on 29th April, I will be giving a talk titled “Monitoring sleep quality with non-invasive sensors“, which is also the title of my recently completed licentiate thesis. The time is 1.15pm, the location is Tietotekniikan talo (Computer Science building, hall T2) at the Aalto University campus in Otaniemi, it’s likewise free entry, and the beer offer stands for this occasion as well. Welcome.

Intel Inside, Stickers Outside

Bob Keefe really stepped into it when he dared to ask about Apple’s decision of not putting “Intel Inside” stickers on Macs. John Gruber said it was a “dumb question but such a great answer“. (Was it either?) Cult of Mac said the question “stood out for its ineptitude“. Others chimed in with similar disdain. Note that Keefe didn’t actually question the wisdom of this decision – he simply wanted to know the rationale behind it. (He may have also been curious as to how Apple got away with it.) The question was asked in 2007, but got recent publicity on Daring Fireball in a vaguely related post on Kindle ads.

Quite coincidentally, I pondered this question myself only a few days ago. I bought recently a new PC laptop to replace the MacBook Pro I turned into an insurance event with some sleight of hand involving a glass of water. (Note to self: keep liquids well away from delicate electronic equipment.)

Said laptop had six stickers on it: one indicating the model (still there for the time being), “Bluetooth” (yay!), “Spill Resistant Keyboard” (this is the one sticker I wish had been on my MacBook Pro), “Green IT” (whatever that means), “Windows something or other” (as an aside, I am proud to report this PC has never run Windows for even a little bit) and of course “Intel Inside”. Peeling the stickers off, I couldn’t help but recall the sadly departed MBP, which had exactly no stickers.

Are the stickers there for the people who buy the camera with the most megapixels? Possibly. I think they’re there because someone somewhere showed a Powerpoint stack which unequivocally stated that according to statistics, the stickers will have a positive influence on the target demographic in this market segment. It seems Apple is doing quite OK without them though.