Hi guys, I am in charge of a postfix box which acts as a antivirus/antispam relay and smarthost for an exchange 2000 server sitting behind it. For some reason exchange is having trouble sending through it, and I just want to be sure that the problem is not on my side. Here's what my logs say. Firstly, I get plenty of these: Aug 18 13:47:11 post postfix/smtpd[19885]: connect from srv-mail.example.com[192.168.3.3] Aug 18 13:47:11 post postfix/smtpd[19885]: disconnect from srv-mail.example.com[192.168.3.3] and then something like this: Aug 18 00:21:28 post postfix/smtpd[11364]: connect from srv-mail.example.com[192.168.3.3] Aug 18 00:21:28 post postfix/smtpd[11364]: B8926100ED: client=srv-mail.example.com[192.168.3.3] Aug 18 00:26:28 post postfix/smtpd[11364]: timeout after DATA from srv-mail.example.com[192.168.3.3] Aug 18 00:26:28 post postfix/smtpd[11364]: disconnect from srv-mail.example.com[192.168.3.3] Has anybody seen this behaviour, know where to start looking? I'll include my main.cf Thanks main.cf: queue_directory = /var/spool/postfix command_directory = /usr/sbin daemon_directory = /usr/lib/postfix mail_owner = postfix unknown_local_recipient_reject_code = 550 debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin xxgdb $daemon_directory/$process_name $process_id & sleep 5 sendmail_path = /usr/sbin/sendmail newaliases_path = /usr/bin/newaliases mailq_path = /usr/bin/mailq setgid_group = maildrop html_directory = /usr/share/doc/packages/postfix/html manpage_directory = /usr/share/man sample_directory = /usr/share/doc/packages/postfix/samples readme_directory = /usr/share/doc/packages/postfix/README_FILES inet_protocols = all biff = no mail_spool_directory = /var/mail canonical_maps = hash:/etc/postfix/canonical virtual_maps = hash:/etc/postfix/virtual relocated_maps = hash:/etc/postfix/relocated transport_maps = hash:/etc/postfix/transport sender_canonical_maps = hash:/etc/postfix/sender_canonical masquerade_exceptions = root masquerade_classes = envelope_sender, header_sender, header_recipient myhostname = post.example.com program_directory = /usr/lib/postfix inet_interfaces = all masquerade_domains = mydestination = $myhostname,localhost.$mydomain,$mydomain, relevant.domains defer_transports = disable_dns_lookups = no relayhost = isp.relay.host mailbox_command = /usr/bin/procmail -a "$EXTENTION" mailbox_transport = smtpd_sender_restrictions = hash:/etc/postfix/access smtpd_client_restrictions = smtpd_helo_required = yes smtpd_helo_restrictions = strict_rfc821_envelopes = no smtpd_recipient_restrictions = permit_mynetworks, permit_auth_destination, reject_unauth_destination, reject_unknown_sender_domain, reject smtp_sasl_auth_enable = no smtpd_sasl_auth_enable = no smtpd_use_tls = no smtp_use_tls = no alias_maps = hash:/etc/aliases mailbox_size_limit = 0 message_size_limit = 10240000 relay_domains = hash:/etc/postfix/relay_domains