If I enter a special character in the Visual tab, like an em-dash or curly quotes, they remain just the same in the Text tab... i.e. NOT converted to
“ and while that displays OK on the site, I send some pages via a mailing list program - Dada Mail - which expects proper HTML code, something it evidently doesn't get in these cases. The result is a lot of "Â", and other weird characters, in the resulting email. Sometimes this even happens around simple things like a period, if it's been pasted in from another program.
I guess what I really am asking for is a way to convert these special characters into their corresponding HTML automatically. Or, at least, when the user clicks the Text tab or something. I have searched for a plugin that might achieve this, but all I find are ones that go the other way - they preserve HTML already entered in on the Text side. My clients generally won't be using that side, or dealing with any HTML, and I don't want them to have to. But this glitchy-character issue keeps rearing its ugly head when they want to send a mailout.
[EDIT] Looking deeper into this, it looks like a modification to the behaviour of the TinyMCE editor might be all I need. I have looked at the codex article about TinyMCE, but I'm stuck - is there an option to achieve this sort of behaviour? I.E. convert typed special characters (or at least the most common ones, like curly quotes and em-dashes) to HTML entities?