Cannot send email to external source!

[nabilrt]

Hello!, I have configured docker-mailserver, now i can send email to domain to domain such as info@mail.example.com to info1@mail.example.com, but i cannot send email to @gmail.com or other domains.

my docker-compose.yml
version: '2.0'

services:
mailserver:
image: docker.io/mailserver/docker-mailserver:latest
container_name: mailserver
# If the FQDN for your mail-server is only two labels (eg: example.com),
# you can assign this entirely to hostname and remove domainname.
hostname: mail.docacamedia.com # replace with your domain
domainname: mail.docacamedia.com # replace with your domain
dns: 1.1.1.1 # This line is newly added and recommended
env_file: mailserver.env
# More information about the mail-server ports:
# https://docker-mailserver.github.io/docker-mailserver/latest/config/security/understanding-the-ports/
# To avoid conflicts with yaml base-60 float, DO NOT remove the quotation marks.
ports:
- "25:25" # SMTP (explicit TLS => STARTTLS)
- "143:143" # IMAP4 (explicit TLS => STARTTLS)
- "465:465" # ESMTP (implicit TLS)
- "587:587" # ESMTP (explicit TLS => STARTTLS)
- "993:993" # IMAP4 (implicit TLS)
volumes:
- ./docker-data/dms/mail-data/:/var/mail/
- ./docker-data/dms/mail-state/:/var/mail-state/
- ./docker-data/dms/mail-logs/:/var/log/mail/
- ./docker-data/dms/config/:/tmp/docker-mailserver/
- /etc/localtime:/etc/localtime:ro
- /etc/letsencrypt/:/tmp/ssl:ro # Add this line. It will be used later.
restart: always
stop_grace_period: 1m
cap_add:
- NET_ADMIN

[casperklein]

I don't think this issue is DMS related. Probably a local host firewall or your internet provider is blocking port 25.

You can manually test this either from your host or the container with: nc -C 142.250.123.26 25

[nabilrt]

can i send with port 587 instead of 25? If so, do you have any tip fo that?

[casperklein]

No, port 25 is mandatory.

[nabilrt]

Can you help me with a guide to unblock port 25 on ubuntu 20.04?
I have a postfix-main.cf file with the following config
mydestination = localhost.$mydomain, localhost

Referring to this issue, it solved my internal mail sending and recieving email from external source issues. But i still can't send email to external sources such as Gmail etc.
#1278

[casperklein]

Unless you configured it, there should be nothing blocking outbound traffic in Ubuntu. It's more likely, that your ISP blocks the traffic.

[BozhanL]

It seems that your email server is hosted in Digital Ocean, which blocks port 25