So LJ moves. This changes not only their physical location but also their IP address. Suddenly, AOL and Yahoo and a whole bunch of other e-mail providers are all 'WTF, mate? They say they're LJ, but it's a different IP address! SPAMMER!' and then SpamCop gets in on the action. So they're all pointing fingers and yelling 'SPAMMER!' at LJ, and LJ's all 'No, seriously, it's us! IT'S US! WE JUST MOVED! ... *snif* ... nobody listens to us... '
Meanwhile, LJ's e-mail server is all 'Goddammit, that one fucking bounced again. *sigh* I'll send it later.' Six million messages later, half of them (the ones to AOL) have bounced, and the e-mail server is all 'SHIT! You mean I've got to send out all these current comments AND I've got to dig up all the ones that bounced? ... Fuck that. I'm getting more coffee
So LJ geeks have figured out why the e-mail server started throwing a hissyfit, kicked themselves in the asses for not figuring it out sooner, retrieved the e-mail server from its extended