Dear all, I just installed mailcow today and it looks great. I have only one problem regarding receiving emails from external domains. send from mydomain to mydomain: works send from mydomain to external domain e.g. gmail: works receive to mydomain from mydomain: works receive to mydomain from external domain e.g. gmail: does not work I am using namecheap DNS and a server1 with nginx reverse proxy that forward to server2 which has the email server. Mailcow ports in server1 and server2 are opened. Any help is appreciated 🙂 Best regards!

Email receiving not working from external domains

idhamari

Dear all,

I just installed mailcow today and it looks great. I have only one problem regarding receiving emails from external domains.

send from mydomain to mydomain: works
send from mydomain to external domain e.g. gmail: works
receive to mydomain from mydomain: works
receive to mydomain from external domain e.g. gmail: does not work

I am using namecheap DNS and a server1 with nginx reverse proxy that forward to server2 which has the email server. Mailcow ports in server1 and server2 are opened.
Any help is appreciated 🙂
Best regards!

posixaz

You have to check your MX records,MX must point to mailcow server ,also check reverse proxy settings

idhamari

posixaz

I have only one public IP. The mailcow server uses the same public IP of server1. Also namecheap does not allow IP, only domain e.g. mail.,ydomain.com

,also check reverse proxy settings

the reverse proxy works, I can access mailcow interface from external networks. The problem is only when recieving emails from external networks.

posixaz

idhamari i mean check tcp 25 and 465 on reverse proxy

idhamari

posixaz

This is what my reverse proxy in server1 one looks like looks like:
`

server {

   server_name mail.mydomain.com;

   listen 25;
   listen 465;
   listen 587;
   listen 143;
   listen 993;
   listen 110;
   listen 995;
   listen 4190;

    proxy_set_header   X-Real-IP $remote_addr;
    proxy_set_header   X-Scheme $scheme;
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header   X-Forwarded-Proto $scheme;
    proxy_set_header   X-Forwarded-Port $server_port;
    proxy_set_header   Host $http_host;

   location / {
     proxy_pass http://local_ip_mailcow_server/;
   }

listen [::]:443 ssl; # managed by Certbot
listen 443 ssl; # managed by Certbot
ssl_certificate ...letsencrypt/live/...
ssl_certificate_key ...letsencrypt/live/...
include ...letsencrypt/options-ssl-nginx.conf; # managed by Certbot
ssl_dhparam ...letsencrypt/ssl-dhparams.pem; # managed by Certbot
 }
 server {
     if ($host = mail.mydomain.com) {
       return 301 https://$host$request_uri;
   } # managed by Certbot
   listen 80;
   listen [::]:80;
   server_name mail.mydomain.com;
   return 404; # managed by Certbot
  }

posixaz

idhamari you can try telnet from outside to your 25 port to prove is your postfix-mailcow 25 port accessible from outside

idhamari

I got this using: telnet public-ip

telnet: Unable to connect to remote host: No route to host

and I got this using nmap -sS public-ip

PORT STATE SERVICE
25/tcp open smtp
80/tcp open http
110/tcp open pop3
143/tcp open imap
443/tcp open https
465/tcp open smtps
587/tcp open submission
993/tcp open imaps
995/tcp open pop3s

posixaz

telnet public-ip 25

idhamari

I got Connected to public-ip
Escape character is ‘^]’.

posixaz

you have to see your smtp greeting banner like

220 your server ESMTP Postcow

posixaz

maybe this example will helpp you

https://docs.nginx.com/nginx/admin-guide/mail-proxy/mail-proxy/

idhamari

posixaz

Thanks a lot, I will check that!

idhamari

I fixed the nginx but I still have the same behavior.

I can send/receive to/from mailcow to mailcow
I can send to google but not recieve with this error:

The response from the remote server was:
530 5.7.1 Authentication required

I can not send/recieve from yahoo