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
Insert logs in pastebin.com and attach links and you can open ticket on git.