Nodemailer - Cannot send message - smtp connection socket is already destroyed.

[wguerram]

Hello, I created a class to send emails, I instantiante this class when the application starts. My assumption is that the instance will keep the transport open but sometimes I get the error Cannot send message - smtp connection socket is already destroyed.

I'm using ElysiaJS, so I don't know if I'm doing it wrong. I'm using pooling config in Nodemailer.

I run this in my entry file

/**
 * Connect to Mail
 */
initializeMail().catch((error) => {
  console.error('Failed to connect to mail: ' + error.message);
});

My initialize code in a separate file:

export const initializeMail = async () => {
  const mailService = MailService.getInstance();

  await mailService.createConnection();

  mailService
    .verifyConnection()
    ?.then(() => {
      console.log('Mail verified.');
    })
    .catch((err) => {
      console.error('Failed to verify mail: ' + err.message);
    });
};

The class below:

export class MailService {
  private static instance: MailService;
  private transporter?: nodemailer.Transporter;

  private constructor() {}
  //INTSTANCE CREATE FOR MAIL
  static getInstance() {
    if (!MailService.instance) {
      MailService.instance = new MailService();
    }
    return MailService.instance;
  }

  //CREATE CONNECTION FOR LOCAL
  async createLocalConnection() {
    let account = await nodemailer.createTestAccount();
    this.transporter = nodemailer.createTransport({
      host: account.smtp.host,
      port: account.smtp.port,
      secure: account.smtp.secure,
      auth: {
        user: account.user,
        pass: account.pass,
      },
    });
  }

  //CREATE CONNECTION FOR LIVE
  async createConnection() {
    const transportOptions = {
      pool: process.env.SMTP_POOL === 'true' ? true : false,
      maxConnections: Number(process.env.SMTP_MAX_CONNECTIONS) || 5,
      host: process.env.SMTP_HOST,
      port: Number(process.env.SMTP_PORT) || 0,
      secure: process.env.SMTP_TLS === 'true' ? true : false,
      auth: {
        user: process.env.SMTP_USERNAME,
        pass: process.env.SMTP_PASSWORD,
      },
      tls: {
        // do not fail on invalid certs
        rejectUnauthorized: false,
      },
    };

    this.transporter = nodemailer.createTransport(transportOptions);
  }

  //SEND MAIL
  async sendMail(options: MailInterface) {    
    return this.transporter?.sendMail({
      from: options.from || process.env.SMTP_SENDER,
      to: options.to,
      cc: options.cc,
      bcc: options.bcc,
      subject: options.subject,
      text: options.text,
      html: options.html,
    });
  }
  //VERIFY CONNECTION
  verifyConnection() {
    return this.transporter?.verify();
  }

  //CREATE TRANSPOTER
  getTransporter() {
    return this.transporter;
  }
}