This issue doesn't seem to have been raised in the bug tracker yet:
When I paste text containing straight quotation marks, I would expect
them to be automatically converted to a "\begin_inset Quotes eld" (or
erd). If Unicode text is pasted and it contains curly quote
characters, I would expect the same conversion. Or at the very least,
an "educate quotes" menu option would be useful that finds all
quotation marks (including curly characters) and replaces them with
the proper insets.
My workaround is to define a keyboard shortcut linked to the command:
command-sequence buffer-begin; word-find-forward \"; word-find-forward
“; word-find-forward ”; quote-insert;
(The \" escape is necessary for some reason to enter a " in the
dialog. The second two finds are for the left and right curly double
quotes, which might not show up in your email correctly.) I then press
that shortcut repeatedly until all quotes have been educated. Is there
a better option?
-Michael Zahniser