Error 554 554 5.7.1

Thats what I thought... I haven't been able to get my Domain name to forward to my FQDN.
Here is the output - I have been testing this by replying to a message sent from the server.

command_directory = /usr/sbin
config_directory = /etc/postfix
content_filter = smtp-amavis:[127.0.0.1]:10024
daemon_directory = /usr/libexec/postfix
debug peerlevel = 2
enable serveroptions = yes
html_directory = no
inet_interfaces = all
mail_owner = _postfix
mailbox sizelimit = 0
mailbox_transport = cyrus
mailq_path = /usr/bin/mailq
manpage_directory = /usr/share/man
maps rbldomains =
message sizelimit = 20971520
mydomain = mydomain.us
mydomain_fallback = localhost
myhostname = server.mydomain.us
mynetworks = 127.0.0.0/8,192.168.0.0/16
newaliases_path = /usr/bin/newaliases
queue_directory = /private/var/spool/postfix
readme_directory = /usr/share/doc/postfix
sample_directory = /usr/share/doc/postfix/examples
sendmail_path = /usr/sbin/sendmail
setgid_group = _postdrop
smtpd clientrestrictions = permit_mynetworks reject rblclient zen.spamhaus.org permit
smtpd enforcetls = no
smtpd pw_server_securityoptions = cram-md5
smtpd recipientrestrictions = permit sasl_authenticated,permit_mynetworks,reject_unauthdestination,permit
smtpd sasl_authenable = yes
smtpd tls_certfile = /etc/certificates/server.mydomain.us.crt
smtpd tls_keyfile = /etc/certificates/server.mydomain.us.key
smtpd use_pwserver = yes
smtpd usetls = yes
unknown local_recipient_rejectcode = 550

Thanks, that worked.

Is that always required with leopard setup, or is there a DNS/MX issue?

Got another error, don't know if its related

554 5.7.1 Service unavailable; Client host [ISP.Dynamic.IP.Here] blocked using zen.spamhaus.org

Externally my users Dynamic IP's are on zen's blacklist, and since the IP's are Dynamic there is no point in allowing them.

Any help pointing me in the right direction would be great.