Postfix with Sparkpost: SMTP error (554): Client host rejected: Access denied

Accessing the Roundcube, I receive emails but when I go to respond, the error message appears
SMTP Error (554): Failed to add recipient "[email protected]" (5.7.1 <localhost[127.0.0.1]>: Client host rejected: Access denied).

/etc/postfix/main.cf

Code:

inet_protocols = ipv4
#content_filter = amavis:[127.0.0.1]:10024
#receive_override_options = no_address_mappings
milter_protocol = 2
milter_default_action = accept
smtpd_milters = inet:localhost:12301
non_smtpd_milters = inet:localhost:12301

#compatibility
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_delay_reject = yes
smtpd_sender_restrictions =
permit_mynetworks,
reject_non_fqdn_sender,
reject_unknown_sender_domain,
check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf,
permit
smtpd_client_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_unknown_client_hostname,
check_client_access mysql:/etc/postfix/mysql-virtual_client.cf,
permit

smtpd_use_tls = yes
relayhost =


#new code:
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_delay_reject = yes
smtpd_sender_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_non_fqdn_sender,
reject_unknown_sender_domain,
check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf,
permit
smtpd_client_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_unknown_client_hostname,
check_client_access mysql:/etc/postfix/mysql-virtual_client.cf,
permit

# end of file
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
sender_dependent_relayhost_maps = hash:/etc/postfix/relayhost_maps
smtp_sasl_security_options = noanonymous

/etc/postfix/sasl_passwd.

Code:

[smtp.sparkpostmail.com]:587 SMTP_Injection:API_KEY

/etc/postfix/relayhost_maps

Code:

@site.com [smtp.sparkpostmail.com]:587

/etc/postfix/master.cf

Code:

smtp inet n - - - - smtpd
2525 inet n - - - - smtpd

#old code
#submission inet n - - - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
#
# -o smtpd_client_restrictions=permit_sasl_authenticated,reject
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING


#new code
submission inet n - - - - smtpd
-o syslog_name=postfix/submission
-o smtpd_enforce_tls=no
-o smtpd_tls_security_level=may
-o smtpd_tls_auth_only=no
-o smtpd_sasl_auth_enable=yes
-o smtpd_client_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING

After that, run the commands.
> postmap /etc/postfix/sasl_passwd
> postmap /etc/postfix/relayhost_maps
> /etc/init.d/postfix restart

tail /var/log/mail.log

Code:

Jun 28 23:15:10 server postfix/submission/smtpd[17340]: connect from localhost[127.0.0.1]
Jun 28 23:15:10 server postfix/trivial-rewrite[17342]: warning: database /etc/postfix/relayhost_maps.db is older than source file /etc/postfix/relayhost_maps
Jun 28 23:15:10 server postfix/submission/smtpd[17340]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 554 5.7.1 <localhost[127.0.0.1]>: Client host rejected: Access denied; from=<[email protected]> to=<[email protected]> proto= ESMTP helo=<_>
Jun 28 23:15:10 server postfix/submission/smtpd[17340]: disconnect from localhost[127.0.0.1]

Where can I be wrong? How to verify this issue...