SMTP Transport

To use the SMTP transport, which is a protocol several email services supports, install nodemailer via NPM:

npm i nodemailer --save

Next, setup a mailer in the mailers object in config/mail.js, the name of the mailer can be anything but you can use smtp as well:

// config/mail.js
mailers: {
  smtp: {
    transport: 'smtp'
  }
}

Also set the default option in config/mails.js to smtp or whatever name you call the mailer above.

// config/mails.js
default: 'smtp'

SMTP credentials

To set the SMTP credentials, you have a couple of options:

Environment variables

Set the following environment variables:

MAIL_HOST=sandbox.smtp.mailtrap.io
MAIL_PORT=2525
MAIL_USERNAME=username
MAIL_PASSWORD=password

local.js

In development, you can specify a mailer of the same name in local.js so as to override the credentials like username, port etc specified in config/mail.js

// config/local.js
mail: {
  mailers: {
    smtp: {
      host: 'sandbox.smtp.mailtrap.io',
      username: 'username',
      password: 'password',
      port: 2525
    }
  }
}

config/mail.js

You can set your credentials within the mailer defintion as well:

// config/mail.js
mailers: {
  smtp: {
    transport: 'smtp',
    host: 'sandbox.smtp.mailtrap.io',
    username: process.env.MAIL_USERNAME,
    password: process.env.MAIL_PASSWORD,
    port: 2525
  }
}

Notice that for the username and password credentials we are still using environment variables as its best practice not to add secrets to your codebase.