# File lib-plugins/yapra/plugin/publish/imap.rb, line 79
    def encode_field field
      field.gsub(/[^\x01-\x7f]*/) {|x|
        x.scan(/.{1,10}/).map {|y|
          "=?UTF-8?B?" + y.to_a.pack('m').chomp + "?="
        }.join("\n ")
      }
    end