qmail, redhat, ssh, and vim

the symptom: qmail isn't delivering any outgoing mail, and is processing local mail slowly, without any indication in the logs as to why.

the problem: a version of vim compiled with the python interface is sucking up all of the cpu time after the controlling terminal (an ssh session) was disconnected. this bug exists in the version of vim packaged by red hat for 7.3, at least. the bug is explained in the vim faq.

the solution: kill the out-of-control vim.

needless to say, drawing the line between the symptoms and the solution took quite a few more zigs and zags.