Just a couple of postfix questions. Thanks in advance for any replies.
Setup: Centos 7 - minimal install on SSD VPS
I noticed, when setting up a second server for DNS and backups that Webmin installs Postfix version 2.6 and my primary server with Virtualmin uses Postfix version 2.10. I re-installed Postfix with yum but the version number remains at version 2.10. Is this something specific to Virtualmin base repo?
After many nights of reading I have come to the conclusion that port 587 is only needed for submission when using email clients such as Thunderbird. As I only use Usermin I presume I only need to open Dovecot ports in my firewall - ports 143 and 993 (email is sending and receiving ok from within Virtualmin).
When running the Virtualmin install.sh script, it installs the Postfix version available to your distro.
In the case you’re seeing there, I suspect that your second server may be running a different distribution than your new CentOS 7 server.
For example, CentOS 6 comes with Postfix 2.6.6, is that perhaps what you’re running there?
Regarding the email ports – if you only use Usermin, you may not need to open any Dovecot-related ports in your firewall. Those ports wouldn’t need to be remotely accessible, they’d just need to be accessible from the server itself – and to do that, you shouldn’t need to tweak the firewall.