docker-mailserver/docs/content/config/troubleshooting/debugging.md

..todo.. - Please contribute more to help others debug this package

Invalid username or Password

1. Login Container

docker exec -it <mycontainer> bash

2. Check log files

/var/log/mail could not find any mention of incorrect logins here neither in the dovecot logs

3. Make sure you set your hostname to 'mail' or whatever you specified in your docker-compose.yml file or else your FQDN will be wrong

Installation Errors

1. During setup, if you get errors trying to edit files inside of the container, you likely need to install vi:

sudo su
docker exec -it <mycontainer> apt-get install -y vim

Testing Connection

I spent HOURS trying to debug "Connection Refused" and "Connection closed by foreign host" errors when trying to use telnet to troubleshoot my connection. I was also trying to connect from my email client (macOS mail) around the same time. Telnet had also worked earlier, so I was extremely confused as to why it suddenly stopped working. I stumbled upon fail2ban.log in my container. In short, when trying to get my macOS client working, I exceeded the number of failed login attempts and fail2ban put dovecot and postfix in jail! I got around it by whitelisting my ipaddresses (my ec2 instance and my local computer)

sudo su
docker exec -ti mail bash
cd /var/log
cat fail2ban.log | grep dovecot

# Whitelist ip addresses:
fail2ban-client set dovecot addignoreip <server ip>  # ec2 cloud server
fail2ban-client set postfix addignoreip <server ip>
fail2ban-client set dovecot addignoreip <client ip>  # my desktop
fail2ban-client set postfix addignoreip <client ip>

# this will delete the jails entirely - nuclear option
fail2ban-client stop dovecot
fail2ban-client stop postfix

No Mail?

I finally got my macOS client working, but was not receiving test messages. I edited docker-compose.yml and temporarily disabled the spam filter (and fail2ban). Now I am getting mail. I will troubleshoot those and re-enable them next week, but thought this might be of help for others trying to troubleshoot.

    environment:
    - ENABLE_MANAGESIEVE=0
    - ENABLE_FAIL2BAN=0