Mail send error

I have a mail server,
Features and installed systems are as follows:
Ubuntu 20.x
Nginx
Roundcube
Iredadmin
Postfix
Dovecot v.s

I’m having trouble sending mail

Here is the error I got:
<mail.xxxxx.com[127.0.0.1]>: Client host rejected: Access denied (in
reply to RCPT TO command)

postfix main.cf:

relayhost = [mail.xxxx.com]:587
smtpd_sasl_auth_enable = yes
smtpd_use_tls = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_security_level = may
header_size_limit = 4096000
smtpd_sasl_security_options = noanonymous

Waiting for your help, thanks