How to send mail without using email-credentials via nodemailer npm in nodejs?

I know how to send mail using nodemailer but I am using email credentials of that, but I don't want to use that. Is there any other method of sending mails.

My nodemailer code snippet is

var nodemailer = require('nodemailer');

// Not the movie transporter!
  var transporter = nodemailer.createTransport({
      service: 'gmail',
      auth: {
          user: 'vikaskohli@email.com', // Your email id
          pass: 'password' // Your password
      }
  });

module.exports =
{
   sendEmail: function sendMail(varhtml,vartext, varsubject,varfrom, varfrom_name,varto, varto_name, reply_to_email ) {


       //setup e-mail data with unicode symbols
       var mailOptions = {
            from: varfrom_name, // sender address
          // to: ['vikaskohli@email.com','vikaskohli1@email.com'], // list of receivers
               // to: ['vikaskohli@email.com,vikaskohli1@email.com'], // list of receivers
               // to: 'vikaskohli@email.com','vikaskohli1@email.com', // list of receivers
           to: varto, // list of receivers
           subject: varsubject, // Subject line
           text: vartext, // plaintext body
           html: varhtml // html body
       };


       console.log(mailOptions);

       // send mail with defined transport object
        transporter.sendMail(mailOptions, function (error, info) {
           if (error) {
               return console.log(error);
           }else{
             return console.log(info);
           }
       });


   }

}

In the above code, also I don't change my sender name. If I want to send from other mail like

vikaskohli3@gmail.com

but it automatically send from that mail for which I have use credentials here

vikaskohli@email.com

Also I tried using sendmail npm, they don't need any credentials but it send mail in the spam folder

My sendmail code snippet

 var sendmail = require('sendmail')({silent: true})
  sendmail({
    from: 'vikaskohli@email.com',
    to: 'vikaskohli@email.com,vikaskohli1@email.com',
    subject: varsubject, // Subject line
    html: varhtml,
    attachments: [
    ]
  }, function (err, reply) {
    console.log(err && err.stack)
    console.dir(reply)
  });

via VIKAS KOHLI