# File lib/mail/message.rb, line 1283 def add_charset if body.only_us_ascii? header[:content_type].parameters['charset'] = 'US-ASCII' else warning = "Non US-ASCII detected and no charset defined.\nDefaulting to UTF-8, set your own if this is incorrect.\n" STDERR.puts(warning) header[:content_type].parameters['charset'] = 'UTF-8' end end