I have a problem with PHP send email to MailHog inside docker container.

Test with:

• Macbook M1
• php:8.1.29-cli
• maihog/mailhog:latest
• PHPMailer

// run.php

use PHPMailerPHPMailerPHPMailer;
use PHPMailerPHPMailerSMTP;
use PHPMailerPHPMailerException;

//Load Composer's autoloader
require 'vendor/autoload.php';

$mail = new PHPMailer(true);

$mail->SMTPDebug = SMTP::DEBUG_SERVER;
$mail->isSMTP();
$mail->Host      = 'localhost';
$mail->SMTPAuth  = false;
$mail->Username  = null;
$mail->Password  = null;
$mail->Port      = 1025;

//Recipients
$mail->setFrom('[email protected]', 'Test Sender');
$mail->addAddress('[email protected]', 'Test Receiver');

//Content
$mail->isHTML(true);
$mail->Subject = 'Here is the subject';
$mail->Body    = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

if(!$mail->send()) {
    echo 'Message could not be sent.';
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Message has been sent';
}

Successfully run on host machine

• I ran Mailhog in a container with port 1025 smtp, 8025 web.
• I was able to send email and mailhog caught that email.

Fail when running in docker.

I have docker compose file.
I have doubt that those all the ports are blocked, so I changed 1025, 8081, 51200…eg. Non of them work.

version: "1.0"
name: worker
services:
  mailhog:
    container_name: "mail_server"
    image: mailhog/mailhog
    ports:
      - 8025:8025
      - 1025:1025
    networks:
      - internet
  cronjob:
    container_name: "workers"
    build:
      context: .
      dockerfile: Dockerfile
    networks:
      - internet
      - proxy-net
    volumes:
      - ./src/logs:/var/www/app/logs
    # command: tail -f /dev/null # Keep container running
    command:
      - php
      - index.php

networks:
  internet:
    driver: bridge

and Dockerfile, I have changed different images from PHP, and other.

ARG WORKDIR=/var/www/app

FROM php:8.1.29-cli
#FROM php:8.1.29-apache
#FROM webdevops/php-apache:8.1

ARG ENV
ARG WORKDIR

RUN apt update && apt install -y libicu-dev && rm -rf /var/lib/apt/lists/*
RUN docker-php-ext-install mysqli pdo_mysql
RUN docker-php-ext-enable mysqli pdo_mysql

RUN docker-php-ext-configure intl && docker-php-ext-install intl

WORKDIR $WORKDIR

COPY ./src ./
COPY ./vendor ./vendor

And the error:

workers      | 2024-06-28 04:44:45  SMTP ERROR: Failed to connect to server: Cannot assign requested address (99)
workers      | 2024-06-28 04:44:45  SMTP Error: Could not connect to SMTP host. Failed to connect to server
workers      | Message could not be sent. Mailer Error: SMTP Error: Could not connect to SMTP host. Failed to connect to serverSMTP server error: Failed to connect to server SMTP code: 99 Additional SMTP info: Cannot assign requested address

Does anyone happen to know what the problem here?