Hi everyone,
I’m running a Mailcow instance hosted on a Debian server within Proxmox. My goal is to make Mailcow accessible online for email clients like Thunderbird, Outlook, and Gmail, but without exposing the Web UI to the internet.
Setup Details:
Server: Debian on Proxmox
Network Configuration:
Router is set to forward ports 25, 587, and 993 and forwarding correctly.
Blocking 80 and 443 to mailcow server.
Testing:
From an external network (completely detached from my local network), I performed a telnet test to my domain and successfully connected.
Telnet Output:
telnet xxxx.xxx (domain name) 587
Trying XX.XX.XX.XX... (IP address)
Connected to xxxx.xxx (domain name).
Escape character is '^]'.
220 mx1.xxxx.xx (domain name) ESMTP Postcow
ehlo
501 Syntax: EHLO hostname
Issues Encountered:
Authentication Failure:
When entering my username and password in email clients (Thunderbird, Outlook, Gmail), I receive an error with username/password incorrect.
Autoconfig Not Working:
I manually set up autoconfig over Nginx, but it’s still not functioning as expected.
Has anyone run into a similar problem or know how to fix the authentication issue? I’d really appreciate any advice or guidance you can share. If there’s any documentation or resources you think might help, please point me in the right direction—I’ve been searching but haven’t found anything that fits this situation.
Thank you in advance for your help!