private static boolean shouldEncodeQuotedPrintable(char ch) {
        return ch >= 128 || ch < 10 || (ch >= 11 && ch < 32) || ch == '=';
    }
TODO: handle especials
<p>
https://www.rfc-editor.org/rfc/rfc2047

@param posInLine starts from 0
@return position
turms-plugins/turms-plugin-push/src/main/java/im/turms/plugin/push/core/smtp/codec/MailEncoder.java