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Mail.app and 32-bit signed integers

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Mail.app does not like it when a mail server reports the NEXTUID to be greater than 2^31 (which is the limit for signed 32-bit integers). I could end this post here, but it’s worth explaining how I got here, and how I fixed it… just incase.

A few weeks back, a faculty member hit quota for his email. This isn’t unheard of, but for some reason, this faculty member hit quota in such a way as to cause Dovecot (the central mail server’s mail service) to rapidly increase the UIDs for his email. I’m guessing something like the following happened.

  1. User is near quota, and receives message
  2. Dovecot writes out message to Inbox, but lazily updates dovecot-uidlist
  3. Delivery of message causes quota full
  4. Dovecot goes to update uidlist, but can’t since the quota is full. Which causes a race condition where it tries repeatedly to write it out, and in the process, increasing the base UID each time
  5. After this repeats a few thousand times, the user gets below quota again, and we end up with a NEXTUID of 3829200751 (yes, 3.8 Billion).

Now, there are two things you can think about this. One, is “this is a dovecot problem”. Well, yes, but… they’ve warned users not to store the uidlist files on quota enforced volumes:

Dovecot can’t currently handle not being able to write the control files, so it will cause problems with filesystem quota. To avoid problems with this, you should place control files into a partition where quota isn’t checked. ((http://wiki2.dovecot.org/MailLocation/Maildir))

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“Server” is a concept, not hardware or software

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Today Apple “announced” Mac OS X 10.7 “Lion” Server, and that it will seemingly be an add-on to 10.7 client. It’s basically always been this way, Apple is just finishing the job (for the last server OS X releases, you could effectively upgrade 10.x client to 10.x server by running the server essentials install).

Before we get into the post too much, let me start with an analogy that will lay a bit of the groundwork further on. Go to a restaurant and tell me the difference between your waiter, and the hostess (can’t think of a gender neutral word for this position). The hostess doesn’t bring you your food, they just seat you and maybe bring you water. But, is there really much difference between the two? Could the hostess just as easily wait tables? Or the waiter become the hostess? Sure! Or, they could even be a patron (client) and eat the food given to them by other waiters.

Since the “announcement” (I say it in quotes because basically, all that happened was marketing finally put up a page on the Apple site that acknowledges 10.7 Server will exist, in some form) the two big Apple Server mailing lists (the official one [email protected], and the Mac Enterprise list [email protected]) have been all aflutter with people going apeshit over what is and isn’t listed, the fact that it’s not a separate DVD, etc. Some of this is no doubt left over rage about Apple killing the Xserve, but really, IT people are largely FUD (Fear Uncertainty and Doubt) mongers. You think stock brokers/traders are skittish… if half the people on these lists owned any reasonable amount of Apple stock, the price would be in the news more than Linsey Lohan.

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AirPrint to Airport connected USB printers

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Since iOS 4.2 was released, and AirPrint with it, I’ve wondered whether we’d see an update for the Airport Extreme and Airport Express that would allow AirPrint to USB connected printers, but finding any information on it yielded just speculation about the issue.

So, having never done it before (short of emailing my displeasure about the Xserve being discontinued a bit ago), I shot off an email to [email protected] asking.

What I sent was:

Steve,

AirPrint seems like a pretty darn cool technology, but it seems rather limited in scale at the moment.

Will we see the ability to AirPrint to printers connected to Airport Extreme/Express base stations over USB anytime soon?

Thanks!

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