Subject

I cant receive emails from outside my server.

Description

Im so sorry, to bother you with that topic again… I see there are already a lot of other issues, but I didnt found the right answer for my problem in these…

I have a docker-mailserver running on my IP with this docker-compose.yml:

version: '3.8'

services:
  mailserver:
    image: docker.io/mailserver/docker-mailserver:latest
    container_name: mailserver
    restart: always
    hostname: mail
    domainname: domain.com
    ports:
      - "25:25"
      - "143:143"
      - "465:465"
      - "587:587"
      - "993:993"
    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/
      - /certbot/conf:/etc/letsencrypt
      - /etc/localtime:/etc/localtime:ro
    environment:
      LOG_LEVEL: debug
      ENABLE_AMAVIS: 1
      #AMAVIS_LOGLEVEL: 5
      ENABLE_CLAMAV: 1
      #ENABLE_DNSBL: 1
      ENABLE_FAIL2BAN: 1
      SPOOF_PROTECTION: 1
      POSTMASTER_ADDRESS: my_gmail@gmail.com
      POSTFIX_INET_PROTOCOLS: ipv4
      DOVECOT_INET_PROTOCOLS: ipv4
      ENABLE_SPAMASSASSIN: 1
      SPAMASSASSIN_SPAM_TO_INBOX: 1
      ENABLE_POSTGREY: 1
      ENABLE_SASLAUTHD: 0
      SSL_TYPE: letsencrypt
      ONE_DIR: 1
    cap_add:
      - NET_ADMIN
      - SYS_PTRACE

I have my domain domain.com and my subdomain mail.domain.com. I have added name@domain.com as an email.

I can successfully send emails (everywhere, e.g. gmail), but I can only receive emails from local (name2@domain.com). I can not receive emails from gmail etc. (all tested with thunderbird (explicit TLS - IMAP and ESMTP))

So I think it must be a networking problem… At first I had a look at my server ports with sudo netstat -nlp | grep :25:

tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      27651/docker-proxy
tcp6       0      0 :::25                   :::*                    LISTEN      27658/docker-proxy

that one looked fine, but I also did an external portscan with this website http://www.dnstools.ch/port-scanner.html - port 25 and all the others are open.

My Domain got a MX record for domain.com on mail.domain.com, https://dnschecker.org/mx-lookup.php is confirming its working. SPF and DKIM entries are also successfull, DMARC is not working correctly atm. just still figuring that one out (but I thought it wont fail cuz of this)?

This SSL part is a little bit tricky for me, I know how it works on websites, but dont really know how its used for mailservers… I just created 2 virtual servers inside nginx to get the letsencrypt certificates with certbot… (like for a website) Then I mounted the volume as described in the docs and like in my docker-compose.yml, all my certs are inside of that, not just the cert for the mailserver, but I think that shouldnt be a problem? I have a cert for domain.com and a cert for mail.domain.com, can you explain which one I need? Do I need a cert for the mailserver (so mail.domain.com) or do I need a cert for my used domain (domain.com, as I use the email name@domain.com)? Or both?

I tried to test this with https://ssl-tools.net/mailservers, but it is not checking the certs, I dont know why…

But connecting from thunderbird with TLS/SSL with IMAP and SMTP is working, so I thought there shouldnt be a problem, but as said, my knowledge on that specific topic is limited…

I have kaspersky installed on my pc, and sometimes I get a warning, that the certificate for domain.com is wrong, and when I display it from kaspersky, the certificate is issued for mail.domain.com. Thunderbird got no problems, as I tell kaspersky not to block that connection, thunderbird doesnt bother, so I dont know if that is really an issue or maybe just kaspersky being weired.

So I dont know why its not working and what to do… Glad for any help and sorry to bother! Merry Christmas!