Same here - got this earlier today. I also had a point where I couldn't access the site at all for about 5 mins - don't know if some kind of update is happening?
My co-lo company was replacing some of the power distribution equipment. They thought the osdev.org system wouldn't lose power, just network access for a minute. Seems they where wrong and for some reason the SMTP software (postfix) didn't restart correctly when the system came back on. Should be all fixed now.