anchor.diff:  
           return attachment.file.readAsBytes().then((bytes) {
             // Chunk'd (76 chars per line) base64 string, separated by "\r\n".
  -          var contents = chunkEncodedBytes(base64.encode(bytes));
  +          var contents = chunkEncodedBytes(convert.base64.encode(bytes));
   
             buffer.write('--$boundary\r\n');
             buffer.write(
  
positive.code:       if (ccRecipients != null && !ccRecipients.isEmpty) {
          var cc = ccRecipients.map(Address.sanitize).join(',');
          buffer.write('Cc: $cc\r\n');
        }
  
        if (bccRecipients != null && !bccRecipients.isEmpty) {
          var bcc = bccRecipients.map(Address.sanitize).join(',');
          buffer.write('Bcc: $bcc\r\n');
        }
  
        // Since TimeZone is not implemented in DateFormat we need to use UTC for proper Date header generation time
  
negative.code:   String text;
    String html;
    String identityString = 'mailer';
    Encoding encoding = convert.utf8;
  
    bool _isDelivered = false;
    int _counter = 0;
  