Is it OK to use fonts, i.e bold, italic, in an email to a professor or to any other academic? Is it acceptable or appropriate to use fonts, i.e bold, italic, in an email to an academic in order to do emphasise or organise the text ? 

or would it be perceived as offensive ?
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In summary, unless absolutely necessary, use a plain text. I you feel you need to organise your text it means your email already too long. If it is a draft of the paper, use an attachment.