554 5.7.1 Relay access denied postfix

I have facing problem with send email from cyberpanel rainloop. i'm testing on mx toolbox, its show

Status Ok   SMTP Reverse DNS Mismatch   OK - 170.64.156.12 resolves to mail.kacktus.com.au
Status Ok   SMTP Valid Hostname OK - Reverse DNS is a valid Hostname
Status Ok   SMTP Banner Check   OK - Reverse DNS matches SMTP Banner
Status Ok   SMTP TLS    OK - Supports TLS.
Status Ok   SMTP Connection Time    1.123 seconds - Good on Connection time
Status Ok   SMTP Open Relay OK - Not an open relay.
Status Ok   SMTP Transaction Time   2.368 seconds - Good on Transaction Time

Connecting to 170.64.156.12

220 mail.kacktus.com.au ESMTP Postfix [869 ms]
EHLO keeper-us-east-1d.mxtoolbox.com
250-mail.kacktus.com.au
250-PIPELINING
250-SIZE 30720000
250-ETRN
250-STARTTLS
250-AUTH PLAIN
250-AUTH=PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING [337 ms]
MAIL FROM:<[email protected]>
250 2.1.0 Ok [340 ms]
RCPT TO:<[email protected]>
554 5.7.1 <[email protected]>: Relay access denied [340 ms]

This is postfix config:

myhostname = mail.kacktus.com.au
mynetworks = 170.64.156.12, 127.0.0.0/8
message_size_limit = 30720000
virtual_alias_domains =
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_mailbox_base = /home/vmail
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_use_tls = yes
smtpd_tls_cert_file = /etc/pki/dovecot/certs/dovecot.pem
smtpd_tls_key_file = /etc/pki/dovecot/private/dovecot.pem
virtual_create_maildirsize = yes
virtual_maildir_extended = yes
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_cano>
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
inet_interfaces = all
smtp_tls_security_level = may
disable_vrfy_command = yes
smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = $smtpd_milters
milter_default_action = accept

tls_server_sni_maps = hash:/etc/postfix/vmail_ssl.map

I'm trying long time to find solutions, Can't figure out. im using digitalocean droplet with cyberpanel.

The error message is exactly saying why it is not working. The MX Toolbox is trying to use your server as a relay and your server is not allowing relaying.

If you want to be an open relay (which you should not want), you can add 0.0.0.0/0 to your mynetworks, but for testing purposes from MX Toolbox you can set it temporarily.

Some time ago I made a simple Ansible role to configure a Postfix server, you might useful information there: https://github.com/polatsinan/postfix_server

Especially look for the templates/main.cf.j2 file.