$ npm install react-native-smtp --save

$ react-native link react-native-smtp

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-smtp and add Smtp.xcodeproj
3. In XCode, in the project navigator, select your project. Add libSmtp.a to your project's Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

1. Open up android/app/src/main/java/[...]/MainApplication.java

• Add import com.reactlibrary.SmtpPackage; to the imports at the top of the file
• Add new SmtpPackage() to the list returned by the getPackages() method

2. Append the following lines to android/settings.gradle:

   include ':react-native-smtp'
   project(':react-native-smtp').projectDir = new File(rootProject.projectDir, 	'../node_modules/react-native-smtp/android')
   

3. Insert the following lines inside the dependencies block in android/app/build.gradle:

     compile project(':react-native-smtp')
   

import EmailSender from 'react-native-smtp';

// Configuration
EmailSender.config({
  host: 'smtp.host.io',
  port: '465', // Optional. Default to 465
  username: 'username',
  password: 'password',
  isAuth: 'true', // Optional. Default to `true`
  tls: 'true' // Optional. Default to `true`
});

/*
 * Used react-native-fs module to get file path.
 * Keep this array empty if there is no attachment.
 */
const attachments = [
  RNFS.ExternalStorageDirectoryPath + '/Tracklist/file.txt',
  RNFS.ExternalStorageDirectoryPath + '/Tracklist/file_2.txt',
];

// Now send the mail
EmailSender.send(
  {
    from: '[email protected]',
    to: '[email protected],[email protected]',
    subject: 'The subject',
    body: '<h3> Cool Body </h3>',
    replyTo: '[email protected]' // Optional
  },
  attachments, // This second parameter is mandatory. You can send an empty array.
);