Sorry about that
The problem I talked about below, the runaway email process that was eating my server's brain, got a bellyful. Everything ground to a halt so badly that I couldn't even reboot remotely, and had to put a call in to the ISP to go over and toggle the power switch. The server remained on--well, consuming much power but accomplishing nothing--until it was rebooted a few minutes ago, but from the outside it would've seemed to be simply gone for several hours today.