NEED HELP URGENTLY

Hi, We are running OSX Server 10.3.9 using postfix and Squirrel mail. Now we have been running this for approx 2 1/2 years without any problems. Recently our Local Authority upgraded their firewall and filter system and during this they had quite a few problems which left the network wide open. Since this has happened it now seems as if our OSX Server is being used as a SMTP relay. When I go to console and bring up the SMTP log i just get constant messages being inputted i.e. from weird email address but then most of the messages get put into the deferred folder because of smtpd restrictions. If I go to a SMTP relay test site and put my email server IP or FQDN name in it says that RELAY ACCESS DENIED at the end of the test but something is using the SMTP. I have posted my Postfix Main.cf to assist anybody who can help me. alias_database = hash:/etc/postfix/aliases alias_maps = hash:/etc/postfix/aliases mydomain_fallback = localhost myhostname = mail.salegrammar.co.uk mydomain = salegrammar.co.uk myorigin = $mydomain mailbox_transport = cyrus enable_server_options = yes luser_relay = scr@server.co.uk maps_rbl_domains = sbl-xbl.spamhaus.org,cbl.abuseat.org,bl.spamcop.net,rbl.maps.vix.com message_size_limit = 10240000 mydestination = $myhostname,localhost.$mydomain,localhost,$mydomain,$mydomain smtpd_use_tls = no smtpd_enforce_tls = no smtpd_client_restrictions = hash:/etc/postfix/smtpdreject,__________ smtpd_sasl_local_domain = $mydomain smtpd_sasl_security_options = noanonymous smtpd_tls_loglevel = 0 smtpd_sasl_auth_enable = yes smtpd_use_pw_server = yes smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_pipelining, reject_rbl_client list.dsbl.org, reject_rbl_client sbl-xbl.spamhaus.org, reject_rbl_client cbl.abuseat.org, reject_rbl_client bl.spamcop.net, reject_rbl_client rbl.maps.vix.com, permit smtpd_pw_server_security_options = gssapi,cram-md5,login,plain smtpd_recipient_limit = 10000 server_enabled = 1 relayhost = always_bcc = mynetworks = 127.0.0.1/32,10.15.6.1/32,10.15.0.0/16,10.10.0.0/16,82.0.0.0/8,195.0.0.0/8, 81.0.0.0/8 local_recipient_maps = unknown_local_recipient_reject_code = 450 smtpd_delay_reject = yes smtpd_require_helo = yes smtpd_helo_restrictions = permit_mynetworks,reject_non_fqdn_hostname,reject_invalid_hostname,permit smtpd_sender_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_non_fqdn_sender, reject_unknown_sender_domain,reject_unknown_address,permit smtpd_helo_restrictions = reject_invalid_hostname