You can use postfix + dovecot + roundcube + spamassassin + opendkim + pigeonhole. Maximum stability. Roundcube have aliases plugin.
You can start from here: https://wiki.archlinux.org/title/Virtual_user_mail_system_with_Postfix,_Dovecot_and_Roundcube
Topic starter don’t use docker containers. He use lxc containers. LXC is virtual machines on host kernel. Case is that: He have 3 virtual machines with shared disk. In 3 VMs have 3 different applications. Applications work under different users and can’t rewrite data on shared disk. That is user permissions problem.
the idea is that: all your applications work under the same user. or at least under the same group. because this is exactly how the differentiation of rights is applied.
A good plan is to create some kind of user in all three containers and run qbittorrent, samba and the third application under it.
A bad plan is to run everything under a random user with 777 rights, but this is a really bad plan.
Create a user in all three containers and work under it. That is not hard. Run qbittorent with that user. Config will be there: /home/user/.config . Then set that user for samba. I don’t know third app , but I think you can find how change user in manual.
You can use Revolt. Literaly Discord clone. https://github.com/revoltchat
Russia break into a pile of separate republic is practically impossible, as it will cause colossal pain for literally all states. It is much easier to negotiate with one dictator with a nuclear button than with twenty.
Insert logs in pastebin.com and attach links and you can open ticket on git.