Can't send/receive mails beacause of database error (?)

Hello,
I've been setting up a new server with ISPConfig 3.2, following along this guide: www. howtoforge .com/ispconfig-autoinstall-debian-ubuntu/ .
(Sorry for the scuffed links, I can't post functioning ones because of my account age.)
Now I've run into some issues with sending and receiving mails, sending spits out:

Code:

<localhost.localdomain[127.0.0.1]>: Client host rejected: Server configuration error)

in Roundcube. Mails sent to the server from outside like Gmail don't show up and Gmail does not show any errors that it couldn't deliver the mail.

/var/log/mail.log shows the following when trying to send mails:

Code:

May 16 15:57:02 server postfix/smtpd[708286]: connect from localhost.localdomain[127.0.0.1]
May 16 15:57:02 server postfix/proxymap[705864]: warning: connect to mysql server 127.0.0.1: Access denied for user 'ispconfig'@'localhost' (using password: YES)
May 16 15:57:02 server postfix/smtpd[708286]: warning: proxy:mysql:/etc/postfix/mysql-virtual_client.cf lookup error for "localhost.localdomain"
May 16 15:57:02 server postfix/smtpd[708286]: NOQUEUE: reject: RCPT from localhost.localdomain[127.0.0.1]: 451 4.3.5 <localhost.localdomain[127.0.0.1]>: Client host rejected: Server configuration error; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<localhost>
May 16 15:57:02 server postfix/smtpd[708286]: disconnect from localhost.localdomain[127.0.0.1] ehlo=1 auth=1 mail=1 rcpt=0/1 rset=1 quit=1 commands=5/6

and trying to receive mails:

Code:

May 16 16:04:21 server postfix/smtpd[708286]: connect from mail-ej1-f50.google.com[209.85.218.50]
May 16 16:04:21 server postfix/proxymap[705864]: warning: connect to mysql server 127.0.0.1: Access denied for user 'ispconfig'@'localhost' (using password: YES)
May 16 16:04:21 server postfix/trivial-rewrite[705589]: warning: virtual_alias_domains: proxy:mysql:/etc/postfix/mysql-virtual_alias_domains.cf: table lookup problem
May 16 16:04:21 server postfix/trivial-rewrite[705589]: warning: virtual_alias_domains lookup failure
May 16 16:04:21 server postfix/trivial-rewrite[705589]: warning: virtual_alias_domains: proxy:mysql:/etc/postfix/mysql-virtual_alias_domains.cf: table lookup problem
May 16 16:04:21 server postfix/trivial-rewrite[705589]: warning: virtual_alias_domains lookup failure
May 16 16:04:21 server postfix/proxymap[705864]: warning: connect to mysql server 127.0.0.1: Access denied for user 'ispconfig'@'localhost' (using password: YES)
May 16 16:04:21 server postfix/smtpd[708286]: warning: proxy:mysql:/etc/postfix/mysql-virtual_client.cf lookup error for "mail-ej1-f50.google.com"
May 16 16:04:21 server postfix/smtpd[708286]: NOQUEUE: reject: RCPT from mail-ej1-f50.google.com[209.85.218.50]: 451 4.3.5 <mail-ej1-f50.google.com[209.85.218.50]>: Client host rejected: Server configuration error; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<mail-ej1-f50.google.com>

As there appears to be an auth problem with the database, I've checked that the password for the ispconfig user is correct.
The database credentials in /etc/postfix/mysql-virtual_alias_domains.cf and /etc/postfix/mysql-virtual_client.cf are correct as well.
I've also been following along this guide:
www. howtoforge .com/how-to-install-an-email-server-with-ispconfig-on-debian-10/
, if that provides any useful information.

Since there are some databases on the server, which will get queries from outside of localhost, I've set up TLS for MariaDB using the information provided here: www. cyberciti .biz/faq/how-to-setup-mariadb-ssl-and-secure-connections-from-clients/ .
But as postfix accesses from localhost, I figured it won't need the client certificates (?).

Content from htf_report.txt:

Code:

##### SERVER #####
IP-address (as per hostname): ***.***.***.***
[WARN] could not determine server's ip address by ifconfig
[INFO] OS version is Debian GNU/Linux 11 (bullseye)

[INFO] uptime:  18:31:49 up 3 days,  5:52,  2 users,  load average: 0.38, 0.43, 0.45

[INFO] memory:
               total        used        free      shared  buff/cache   available
Mem:            62Gi        14Gi       5.9Gi       206Mi        41Gi        46Gi
Swap:           31Gi          0B        31Gi

[INFO] systemd failed services status:
  UNIT LOAD ACTIVE SUB DESCRIPTION
0 loaded units listed.

[INFO] ISPConfig is installed.

##### ISPCONFIG #####
ISPConfig version is 3.2.9p1


##### VERSION CHECK #####

[INFO] php (cli) version is 7.4.33
[INFO] php-cgi (used for cgi php in default vhost!) is version 7.4.33

##### PORT CHECK #####


##### MAIL SERVER CHECK #####


##### RUNNING SERVER PROCESSES #####

[INFO] I found the following web server(s):
        Unknown process (nginx:) (PID 714885)
[INFO] I found the following mail server(s):
        Postfix (PID 2278)
[INFO] I found the following pop3 server(s):
        Dovecot (PID 1378)
[INFO] I found the following imap server(s):
        Dovecot (PID 1378)
[INFO] I found the following ftp server(s):
        PureFTP (PID 61128)

##### LISTENING PORTS #####
(only           ()
Local           (Address)
[anywhere]:4190         (1378/dovecot)
[anywhere]:993          (1378/dovecot)
[anywhere]:995          (1378/dovecot)
[localhost]:11332               (1409/rspamd:)
[localhost]:11333               (1409/rspamd:)
[localhost]:11334               (1409/rspamd:)
[localhost]:10023               (709/postgrey)
[anywhere]:587          (2278/master)
[localhost]:6379                (1408/redis-server)
[localhost]:11211               (1382/memcached)
[anywhere]:110          (1378/dovecot)
[anywhere]:143          (1378/dovecot)
[anywhere]:80           (714885/nginx:)

I appreciate any help, also let me know if you need more information.

 

ISPConfig questions should be posted on ISPConfig forum.

Follow these instructions: https://forum.howtoforge.com/threads/please-read-before-posting.58408/

 

I updated the post with the information requested. I posted it here because I figured the question is not ISPConfig specific, but if you think it would be a better fit there, then this post here can be deleted I guess.

 

ISPConfig auto-installer should set up a working e-mail system, so if that failed it is an ISPConfig problem.

How did you do that verification? Did you try to log in to database from localhost as that user?

Did you test before doing those modifications if e-mails are working?
What other configuration changes have you done that were not mentioned in the ISPConfig auto-installer instructions?