リレーアクセスが拒否されました。

postfix/smtpd[15709]: NOQUEUE: reject: RCPT from mydomain[192.166.218.190]:454 4.7.1 
<mailongmail>: Relay access denied; from=<mailondomain> to=<mailongmail> proto=ESMTP helo=<mydomain>

ドメインから別のメールサーバー（Gmailなど）にメールを送信しようとすると、roundcubeでこのエラーが発生します。

会議後-n

alias_database = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
append_dot_mydomain = no
biff = no
body_checks = regexp:/etc/postfix/body_checks
broken_sasl_auth_clients = yes
config_directory = /etc/postfix
content_filter = amavis:[127.0.0.1]:10024
dovecot_destination_recipient_limit = 1
greylisting = check_policy_service inet:127.0.0.1:10023
header_checks = regexp:/etc/postfix/header_checks
html_directory = /usr/share/doc/postfix/html
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
maildrop_destination_concurrency_limit = 1
maildrop_destination_recipient_limit = 1
mime_header_checks = regexp:/etc/postfix/mime_header_checks
mydestination = localhost, localhost.$mydomain
mydomain = xxx.com
myhostname = $mydomain
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 192.168.1.0/24 10.0.0.0/24
myorigin = /etc/mailname
nested_header_checks = regexp:/etc/postfix/nested_header_checks
owner_request_special = no
proxy_read_maps = $local_recipient_maps $mydestination  $virtual_alias_maps $virtual_alias_domains $sender_bcc_maps $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $smtpd_sender_login_maps
readme_directory = /usr/share/doc/postfix
receive_override_options = no_address_mappings
recipient_delimiter = +
relay_domains = mysql:/etc/postfix/mysql-virtual_relaydomains.cf
relay_recipient_maps = mysql:/etc/postfix/mysql-virtual_relayrecipientmaps.cf
relayhost =
sender_bcc_maps = proxy:mysql:/etc/postfix/mysql-virtual_outgoing_bcc.cf
smtp_tls_exclude_ciphers = RC4, aNULL
smtp_tls_protocols = !SSLv2,!SSLv3
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
smtpd_client_message_rate_limit = 100
smtpd_client_restrictions = check_client_access mysql:/etc/postfix/mysql-virtual_client.cf
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, check_helo_access regexp:/etc/postfix/helo_access, reject_invalid_hostname, reject_non_fqdn_hostname, check_helo_access regexp:/etc/postfix/blacklist_helo
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, check_recipient_access mysql:/etc/postfix/mysql-virtual_recipient.cf, reject_rbl_client zen.spamhaus.org
smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, defer_unauth_destination
smtpd_restriction_classes = greylisting
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_path = private/auth
smtpd_sasl_type = dovecot
smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql-virtual_sender_login_maps.cf
smtpd_sender_restrictions = check_sender_access regexp:/etc/postfix/tag_as_originating.re , permit_mynetworks, permit_sasl_authenticated, check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf, check_sender_access regexp:/etc/postfix/tag_as_foreign.re
smtpd_tls_cert_file = /etc/postfix/smtpd.cert
smtpd_tls_exclude_ciphers = RC4, aNULL
smtpd_tls_key_file = /etc/postfix/smtpd.key
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2,!SSLv3
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
transport_maps = hash:/var/lib/mailman/data/transport-mailman, proxy:mysql:/etc/postfix/mysql-virtual_transports.cf
virtual_alias_domains =
virtual_alias_maps = hash:/var/lib/mailman/data/virtual-mailman, proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, proxy:mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_gid_maps = mysql:/etc/postfix/mysql-virtual_gids.cf
virtual_mailbox_base = /var/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_transport = dovecot
virtual_uid_maps = mysql:/etc/postfix/mysql-virtual_uids.cf

私もISPconfig 3を使用します。