There is nothing wrong with telling people that their <insert broken
software package here> is [broken|not-standards-compliant|...] but the
reality is that we can only do that gently as a way to begin educating
others. Case in point: my sister uses hotmail and insists on
top-posting. I pointed out once how this didn't work so well,
demonstrated how to snip and intersperse responses and explained that
it was more "courteous" to do things the "right" way. So, now she
tries, and fails miserably, but she at least has an idea of it and
over time she'll likely come around. Meanwhile, I suffer through
silently knowing that someday she'll get it.