Request to MX server from a docker container - docker

Question

Context
Our solution send emailing campaign, and some email provider makes temporary blacklist because we used inexistant email addresses (they may be created/imported by any user)
Solution
I try to implement a email checker based on https://www.codexworld.com/verify-email-address-check-if-real-exists-domain-php/
Problem
From my local computer, this script works (when my IP is not temporary blacklisted) but from my Docker Container stream_socket_client or even telnet always times out.
As I see, MX servers always time out non verified requester but how can I make it work from my docker container?
I've no specific docker configuration for the port 25.
Thank you
docker-compose.yml
# Base docker-compose file to run required services: Adminer, MySQL, and Redis
version: '3.7'
services:
adminer:
image: adminer:latest
ports:
- "8080:8080"
database:
image: mysql:8.0
volumes:
- db_data:/var/lib/mysql
ports:
- "3306:3306"
environment:
MYSQL_ROOT_PASSWORD: root
cap_add: [ SYS_NICE ] # https://github.com/docker-library/mysql/issues/303
command: ['mysqld', '--character-set-server=utf8mb4', '--collation-server=utf8mb4_general_ci', '--lower_case_table_names=1']
redis:
image: redis:alpine
expose:
- "6379"
redisinsight:
image: redislabs/redisinsight
ports:
- "8081:8001"
reverse-proxy:
image: nginx:alpine
depends_on:
- backend
- frontend
volumes:
- ./../../../backend/infra/etc/nginx/dev.conf:/etc/nginx/nginx.conf
ports:
- "80:80"
backend:
build:
context: ./../..
dockerfile: container/dev/backend.dockerfile
expose:
- "80"
volumes:
- {...}
depends_on:
- database
frontend:
build:
context: ./../..
dockerfile: container/dev/frontend.dockerfile
expose:
- "3000"
volumes:
- {...}
tty: true # required to keep yarn running (https://stackoverflow.com/a/61050994)
volumes:
# Contains the database's data
db_data: {}
# Base docker-compose file to run required services: Adminer, MySQL, and Redis
version: '3.7'
services:
adminer:
image: adminer:latest
ports:
- "8080:8080"
database:
image: mysql:8.0
volumes:
- db_data:/var/lib/mysql
ports:
- "3306:3306"
environment:
MYSQL_ROOT_PASSWORD: root
cap_add: [ SYS_NICE ] # https://github.com/docker-library/mysql/issues/303
command: ['mysqld', '--character-set-server=utf8mb4', '--collation-server=utf8mb4_general_ci', '--lower_case_table_names=1']
redis:
image: redis:alpine
expose:
- "6379"
redisinsight:
image: redislabs/redisinsight
ports:
- "8081:8001"
reverse-proxy:
image: nginx:alpine
depends_on:
- backend
- frontend
volumes:
- ./../../../backend/infra/etc/nginx/dev.conf:/etc/nginx/nginx.conf
ports:
- "80:80"
backend:
build:
context: ./../..
dockerfile: container/dev/backend.dockerfile
expose:
- "80"
volumes:
- {...}
depends_on:
- database
frontend:
build:
context: ./../..
dockerfile: container/dev/frontend.dockerfile
expose:
- "3000"
volumes:
- {...}
tty: true # required to keep yarn running (https://stackoverflow.com/a/61050994)
volumes:
# Contains the database's data
db_data: {}
backend.dockerfile is an ubuntu with git, mysql-client, php