if needEnc {
			b.WriteString("utf-8''")

			offset := 0
			for index := 0; index < len(value); index++ {
				ch := value[index]
				// {RFC 2231 section 7}
				// attribute-char := <any (US-ASCII) CHAR except SPACE, CTLs, "*", "'", "%", or tspecials>
				if ch <= ' ' || ch >= 0x7F ||
					ch == '*' || ch == '\'' || ch == '%' ||
					isTSpecial(rune(ch)) {

					b.WriteString(value[offset:index])
					offset = index + 1