I have my postfix server running with MySQL and squirrelmail, and everything works fine, however when I attempt to send an e-mail from a remote client, I get a relay access denied error, after much googling, I haven't really found anything that solves my problem, I would be grateful for any help that you can give.
me@my-server:~$ postconf -n
alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
append_dot_mydomain = no
biff = no
config_directory = /etc/postfix
delay_warning_time = 4h
disable_vrfy_command = yes
inet_interfaces = all
mailbox_size_limit = 0
maximal_backoff_time = 8000s
maximal_queue_lifetime = 7d
minimal_backoff_time = 1000s
mydestination = my-server, localhost.localdomain, localhost
myhostname = my_domain.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 OTHER_NETWORK HOME_NETWORK
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost = [smtp.comcast.net]:587
smtp_helo_timeout = 60s
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/passwd
smtp_sasl_security_options = noanonymous
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name
smtpd_client_restrictions = permit_mynetworks, permit_sasl_authenticated
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_delay_reject = yes
smtpd_hard_error_limit = 12
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks, permit_sasl_authenticated, warn_if_reject reject_non_fqdn_hostname, reject_invalid_hostname, permit
smtpd_recipient_limit = 16
smtpd_recipient_restrictions = reject_unauth_pipelining, permit_sasl_authenticated, permit_mynetworks, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, permit
smtpd_sasl_type = dovecot
smtpd_sender_restrictions = permit_mynetworks, permit_sasl_authenticated, warn_if_reject reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining, permit
smtpd_soft_error_limit = 3
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
unknown_local_recipient_reject_code = 450
virtual_alias_maps = mysql:/etc/postfix/mysql_alias.cf
virtual_gid_maps = static:5000
virtual_mailbox_base = /var/spool/mail/virtual
virtual_mailbox_domains = mysql:/etc/postfix/mysql_domains.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql_mailbox.cf
virtual_uid_maps = static:5000
