Postfix: "Relay access denied" in maillog when I get email from outside (ex: gmail, yahoo)

Hi All,

I have done many of installation Virtualmin using installer (install.sh) and all works fine.

But few day ago I have installed a new server but I get error on Postfix.
I can send email to inside or to outside server but cannot received a email from outside my server (for example, I send test email from gmail to a email address in my server and I get error)

Here the log in maillog:

 Nov  5 10:03:56 s1 postfix/smtpd[24175]: connect from mail-wg0-f54.google.com[74.125.82.54]
Nov  5 10:03:57 s1 postfix/smtpd[24175]: NOQUEUE: reject: RCPT from mail-wg0-f54.google.com[74.125.82.54]: 554 5.7.1 <support@muahoaqua.vn>: Relay access denied; from=<duongvanchien@gmail.com> to=<support@muahoaqua.vn> proto=ESMTP helo=<mail-wg0-f54.google.com>
Nov  5 10:03:58 s1 postfix/smtpd[24175]: disconnect from mail-wg0-f54.google.com[74.125.82.54]
Nov  5 10:09:19 s1 postfix/smtpd[24669]: connect from sable.websitewelcome.com[192.185.82.128]
Nov  5 10:09:19 s1 postfix/smtpd[24669]: NOQUEUE: reject: RCPT from sable.websitewelcome.com[192.185.82.128]: 554 5.7.1 <info@anhoapulp.com>: Relay access denied; from=<sales@b-electrical.com.au> to=<info@anhoapulp.com> proto=ESMTP helo=<sable.websitewelcome.com>
Nov  5 10:09:19 s1 postfix/smtpd[24669]: disconnect from sable.websitewelcome.com[192.185.82.128]
No

and bellow is postconf -n

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
home_mailbox = Maildir/
html_directory = no
inet_protocols = all
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mydomain = hitech-solutions.vn
myhostname = s1.hitech-solutions.vn
myorigin = $myhostname
newaliases_path = /usr/bin/newaliases.postfix
readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES
relay_domains =
sample_directory = /usr/share/doc/postfix-2.6.6/samples
sender_bcc_maps = hash:/etc/postfix/bcc
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination
smtpd_sasl_auth_enable = yes
transport_maps = hash:/etc/postfix/transport
unknown_local_recipient_reject_code = 550
virtual_alias_maps = hash:/etc/postfix/virtual

I have used whole day today to get it to work, but i think i’m over my head with this one.
Help me please!