Postfix with Docker: Error connecting to SMTP - 454 4.7.1: Relay access denied

So I have the following Setup

Ubuntu 16.04 Server with postfix installed, running BigBlueButton

On that, I have a docker container with Greenlight which is basicly the frontend of BigBlueButton

This Docker Container has the IP 172.18.0.3 (which I added to my networks at the postfix config file)

When I run

docker run --rm --env-file .env bigbluebutton/greenlight:v2 bundle exec rake conf:check

to check if the config and mail is working, I get the following output:

Checking environment: Passed
Checking Connection: Passed
Checking Secret: Passed
Checking SMTP connection: Failed
Error connecting to SMTP - 454 4.7.1 <[email protected]>: Relay access denied

My Greenlight(Docker) SMTP Config in .env File:

SMTP_SERVER=mydomain.example.com
SMTP_PORT=25
SMTP_DOMAIN=mydomain.example.com
#SMTP_USERNAME=
#SMTP_PASSWORD=
#SMTP_AUTH=
SMTP_STARTTLS_AUTO=true

# Specify the email address that all mail is sent from
[email protected]

# Specify the recipient for test emails (needed for providers like Microsoft, who are very
# strict about RFC 2606)
[email protected]

My postfix main.cf File:

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = /usr/share/doc/postfix

# TLS parameters
smtpd_tls_cert_file=/etc/letsencrypt/live/mydomain.example.com/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/mydomain.example.com/privkey.pem
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

mydomain = mydomain.example.com
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mydomain.example.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mydomain.example.com, localhost.example.com, localhost, localhost.localdomain, $mydomain, $myhostname
relayhost =
mynetworks = localhost, 127.0.0.1, 172.18.0.2, 172.18.0.3
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
virtual_mailbox_domains=mydomain.example.com
relay_domains = $mydestination
html_directory = /usr/share/doc/postfix/html

I have tried various changes to mynetworks setting, including setting it to 0.0.0.0 which to my knowledge should allow anyone to send mails - but it still didn't work.

EDIT:

This is my postfix log:

connect from unknown[172.17.0.2]
Nov 17 13:42:58 webinar postfix/smtpd[5604]: NOQUEUE: reject: RCPT from unknown[172.17.0.2]: 454 4.7.1 <[email protected]>: Relay access denied; from=$ from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<mydomain.example.com>

Nov 17 13:42:58 webinar postfix/smtpd[5604]: disconnect from unknown[172.17.0.2] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1 commands=5/6

Solution 1:

Are you certain that you got the IP addresses right? According to your postfix log, the sender is 172.17.0.2, not 172.18.0.3.

Could you add 172.17.0.2 to mynetworks and try again?