==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.5.2
- Deployed with iRedMail Easy or the downloadable installer? downloadable
- Linux/BSD distribution name and version: Ubuntu 20.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): PGSQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Fresh out of the box it says "internal server error" when visiting /iredadmin/

I also get "Unable to connect to the database!" when visiting /mail/

In the postgres logs:

2022-05-10 12:57:17.204 EDT [33996] postgres@template1 ERROR:  encoding "UTF8" does not match locale "en_US"
2022-05-10 12:57:17.204 EDT [33996] postgres@template1 DETAIL:  The chosen LC_CTYPE setting requires encoding "LATIN1".
2022-05-10 12:57:17.204 EDT [33996] postgres@template1 STATEMENT:  CREATE DATABASE vmail WITH TEMPLATE template0 ENCODING 'UTF8';
2022-05-10 12:57:17.204 EDT [33996] postgres@template1 ERROR:  database "vmail" does not exist
2022-05-10 12:57:17.204 EDT [33996] postgres@template1 STATEMENT:  ALTER DATABASE vmail OWNER TO vmailadmin;
2022-05-10 12:57:17.255 EDT [34014] vmailadmin@vmail FATAL:  database "vmail" does not exist
2022-05-10 12:57:17.309 EDT [34032] postgres@vmail FATAL:  database "vmail" does not exist
2022-05-10 12:57:17.361 EDT [34050] vmailadmin@vmail FATAL:  database "vmail" does not exist

And also...

2022-05-10 12:57:42.408 EDT [36214] postgres@postgres LOG:  provided user name (postgres) and authenticated user name (netdata) do not match
2022-05-10 12:57:42.408 EDT [36214] postgres@postgres FATAL:  Peer authentication failed for user "postgres"
2022-05-10 12:57:42.408 EDT [36214] postgres@postgres DETAIL:  Connection matched pg_hba.conf line 104: "local all     postgres   peer"
2022-05-10 12:57:42.425 EDT [36215] postgres@postgres FATAL:  password authentication failed for user "postgres"
2022-05-10 12:57:42.425 EDT [36215] postgres@postgres DETAIL:  Password does not match for user "postgres".
    Connection matched pg_hba.conf line 106: "host  all     all     0.0.0.0/0   md5"
2022-05-10 12:57:42.427 EDT [36216] postgres@postgres FATAL:  password authentication failed for user "postgres"
2022-05-10 12:57:42.427 EDT [36216] postgres@postgres DETAIL:  Password does not match for user "postgres".
    Connection matched pg_hba.conf line 106: "host  all     all     0.0.0.0/0   md5"
2022-05-10 12:57:42.432 EDT [36217] postgres@postgres FATAL:  password authentication failed for user "postgres"
2022-05-10 12:57:42.432 EDT [36217] postgres@postgres DETAIL:  Password does not match for user "postgres".
    Connection matched pg_hba.conf line 106: "host  all     all     0.0.0.0/0   md5"
2022-05-10 12:57:42.435 EDT [36218] postgres@postgres FATAL:  password authentication failed for user "postgres"
2022-05-10 12:57:42.435 EDT [36218] postgres@postgres DETAIL:  Password does not match for user "postgres".