I'm wondering if I've configured something incorrectly. If a user of one domain on my server sends an email to a user on another domain who's DNS records are held by my server but mx records point elsewhere, the mail is sent to my postfix server on the same machine. Is there a way of having postfix check the mx record and send accordingly before checking whether the domain is handled by this machine? postconf -n as follows: alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes config_directory = /etc/postfix inet_interfaces = all inet_protocols = all mailbox_command = procmail -a "$EXTENSION" mailbox_size_limit = 0 mydestination = /etc/mail/local-host-names myhostname = web1.hostfife.net mynetworks = 127.0.0.0/8 myorigin = /etc/mailname recipient_delimiter = + relayhost = smtp_tls_note_starttls_offer = yes smtp_tls_session_cache_database = btree:${queue_directory}/smtp_scache smtp_use_tls = yes smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_local_domain = smtpd_sasl_security_options = noanonymous smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem smtpd_tls_auth_only = no smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key smtpd_tls_loglevel = 1 smtpd_tls_received_header = yes smtpd_tls_session_cache_database = btree:${queue_directory}/smtpd_scache smtpd_tls_session_cache_timeout = 3600s smtpd_use_tls = yes tls_random_source = dev:/dev/urandom setup is postfix on ubuntu server 7. Peter
If you created a site for this domain in ISPConfig, you will have to set the mailserver to external in the site settings (on the options tab) AND also set all co-domains of this site to external mailserver (on the options tabs of every co-domain).