<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <title> Postfix manual - smtp(8) </title> </head> <body> <pre> SMTP(8) SMTP(8) <b>NAME</b> smtp - Postfix remote delivery via SMTP <b>SYNOPSIS</b> <b>smtp</b> [generic Postfix daemon options] <b>DESCRIPTION</b> The SMTP client processes message delivery requests from the queue manager. Each request specifies a queue file, a sender address, a domain or host to deliver to, and recip- ient information. This program expects to be run from the <a href="master.8.html"><b>master</b>(8)</a> process manager. The SMTP client updates the queue file and marks recipi- ents as finished, or it informs the queue manager that delivery should be tried again at a later time. Delivery status reports are sent to the <a href="bounce.8.html"><b>bounce</b>(8)</a>, <a href="defer.8.html"><b>defer</b>(8)</a> or <a href="trace.8.html"><b>trace</b>(8)</a> daemon as appropriate. The SMTP client looks up a list of mail exchanger addresses for the destination host, sorts the list by preference, and connects to each listed address until it finds a server that responds. When a server is not reachable, or when mail delivery fails due to a recoverable error condition, the SMTP client will try to deliver the mail to an alternate host. <b>SECURITY</b> The SMTP client is moderately security-sensitive. It talks to SMTP servers and to DNS servers on the network. The SMTP client can be run chrooted at fixed low privilege. <b>STANDARDS</b> <a href="http://www.faqs.org/rfcs/rfc821.html">RFC 821</a> (SMTP protocol) <a href="http://www.faqs.org/rfcs/rfc822.html">RFC 822</a> (ARPA Internet Text Messages) <a href="http://www.faqs.org/rfcs/rfc1651.html">RFC 1651</a> (SMTP service extensions) <a href="http://www.faqs.org/rfcs/rfc1652.html">RFC 1652</a> (8bit-MIME transport) <a href="http://www.faqs.org/rfcs/rfc1870.html">RFC 1870</a> (Message Size Declaration) <a href="http://www.faqs.org/rfcs/rfc2045.html">RFC 2045</a> (MIME: Format of Internet Message Bodies) <a href="http://www.faqs.org/rfcs/rfc2046.html">RFC 2046</a> (MIME: Media Types) <a href="http://www.faqs.org/rfcs/rfc2554.html">RFC 2554</a> (AUTH command) <a href="http://www.faqs.org/rfcs/rfc2821.html">RFC 2821</a> (SMTP protocol) <a href="http://www.faqs.org/rfcs/rfc2920.html">RFC 2920</a> (SMTP Pipelining) <b>DIAGNOSTICS</b> Problems and transactions are logged to <b>syslogd</b>(8). Cor- rupted message files are marked so that the queue manager can move them to the <b>corrupt</b> queue for further inspection. Depending on the setting of the <b><a href="postconf.5.html#notify_classes">notify_classes</a></b> parameter, the postmaster is notified of bounces, protocol problems, and of other trouble. <b>CONFIGURATION PARAMETERS</b> Changes to <b>main.cf</b> are picked up automatically, as <a href="smtp.8.html">smtp(8)</a> processes run for only a limited amount of time. Use the command "<b>postfix reload</b>" to speed up a change. The text below provides only a parameter summary. See <a href="postconf.5.html">postconf(5)</a> for more details including examples. <b>COMPATIBILITY CONTROLS</b> <b><a href="postconf.5.html#ignore_mx_lookup_error">ignore_mx_lookup_error</a> (no)</b> Ignore DNS MX lookups that produce no response. <b><a href="postconf.5.html#smtp_always_send_ehlo">smtp_always_send_ehlo</a> (yes)</b> Always send EHLO at the start of an SMTP session. <b><a href="postconf.5.html#smtp_never_send_ehlo">smtp_never_send_ehlo</a> (no)</b> Never send EHLO at the start of an SMTP session. <b><a href="postconf.5.html#smtp_defer_if_no_mx_address_found">smtp_defer_if_no_mx_address_found</a> (no)</b> Defer mail delivery when no MX record resolves to an IP address. <b><a href="postconf.5.html#smtp_line_length_limit">smtp_line_length_limit</a> (990)</b> The maximal length of message header and body lines that Postfix will send via SMTP. <b><a href="postconf.5.html#smtp_pix_workaround_delay_time">smtp_pix_workaround_delay_time</a> (10s)</b> How long the Postfix SMTP client pauses before sending ".<CR><LF>" in order to work around the PIX firewall "<CR><LF>.<CR><LF>" bug. <b><a href="postconf.5.html#smtp_pix_workaround_threshold_time">smtp_pix_workaround_threshold_time</a> (500s)</b> How long a message must be queued before the PIX firewall "<CR><LF>.<CR><LF>" bug workaround is turned on. <b><a href="postconf.5.html#smtp_quote_rfc821_envelope">smtp_quote_rfc821_envelope</a> (yes)</b> Quote addresses in SMTP MAIL FROM and RCPT TO com- mands as required by <a href="http://www.faqs.org/rfcs/rfc821.html">RFC 821</a>. <b><a href="postconf.5.html#smtp_skip_5xx_greeting">smtp_skip_5xx_greeting</a> (yes)</b> Skip SMTP servers that greet with a 5XX status code (go away, do not try again later). <b><a href="postconf.5.html#smtp_skip_quit_response">smtp_skip_quit_response</a> (yes)</b> Do not wait for the response to the SMTP QUIT com- mand. Available in Postfix version 2.0 and earlier: <b><a href="postconf.5.html#smtp_skip_4xx_greeting">smtp_skip_4xx_greeting</a> (yes)</b> Skip SMTP servers that greet with a 4XX status code (go away, try again later). <b>MIME PROCESSING CONTROLS</b> Available in Postfix version 2.0 and later: <b><a href="postconf.5.html#disable_mime_output_conversion">disable_mime_output_conversion</a> (no)</b> Disable the conversion of 8BITMIME format to 7BIT format. <b><a href="postconf.5.html#mime_boundary_length_limit">mime_boundary_length_limit</a> (2048)</b> The maximal length of MIME multipart boundary strings. <b><a href="postconf.5.html#mime_nesting_limit">mime_nesting_limit</a> (100)</b> The maximal nesting level of multipart mail that the MIME processor will handle. <b>EXTERNAL CONTENT INSPECTION CONTROLS</b> Available in Postfix version 2.1 and later: <b><a href="postconf.5.html#smtp_send_xforward_command">smtp_send_xforward_command</a> (no)</b> Send the non-standard XFORWARD command when the Postfix SMTP server EHLO response announces XFOR- WARD support. <b>SASL AUTHENTICATION CONTROLS</b> <b><a href="postconf.5.html#smtp_sasl_auth_enable">smtp_sasl_auth_enable</a> (no)</b> Enable SASL authentication in the Postfix SMTP client. <b><a href="postconf.5.html#smtp_sasl_password_maps">smtp_sasl_password_maps</a> (empty)</b> Optional SMTP client lookup tables with one user- name:password entry per remote hostname or domain. <b><a href="postconf.5.html#smtp_sasl_security_options">smtp_sasl_security_options</a> (noplaintext, noanonymous)</b> What authentication mechanisms the Postfix SMTP client is allowed to use. <b>RESOURCE AND RATE CONTROLS</b> <b><a href="postconf.5.html#smtp_destination_concurrency_limit">smtp_destination_concurrency_limit</a> ($<a href="postconf.5.html#default_destination_concurrency_limit">default_destina</a>-</b> <b><a href="postconf.5.html#default_destination_concurrency_limit">tion_concurrency_limit</a>)</b> The maximal number of parallel deliveries to the same destination via the smtp message delivery transport. <b><a href="postconf.5.html#smtp_destination_recipient_limit">smtp_destination_recipient_limit</a> ($<a href="postconf.5.html#default_destination_recipient_limit">default_destina</a>-</b> <b><a href="postconf.5.html#default_destination_recipient_limit">tion_recipient_limit</a>)</b> The maximal number of recipients per delivery via the smtp message delivery transport. <b><a href="postconf.5.html#smtp_connect_timeout">smtp_connect_timeout</a> (30s)</b> The SMTP client time limit for completing a TCP connection, or zero (use the operating system built-in time limit). <b><a href="postconf.5.html#smtp_helo_timeout">smtp_helo_timeout</a> (300s)</b> The SMTP client time limit for sending the HELO or EHLO command, and for receiving the initial server response. <b><a href="postconf.5.html#smtp_xforward_timeout">smtp_xforward_timeout</a> (300s)</b> The SMTP client time limit for sending the XFORWARD command, and for receiving the server response. <b><a href="postconf.5.html#smtp_mail_timeout">smtp_mail_timeout</a> (300s)</b> The SMTP client time limit for sending the MAIL FROM command, and for receiving the server response. <b><a href="postconf.5.html#smtp_rcpt_timeout">smtp_rcpt_timeout</a> (300s)</b> The SMTP client time limit for sending the SMTP RCPT TO command, and for receiving the server response. <b><a href="postconf.5.html#smtp_data_init_timeout">smtp_data_init_timeout</a> (120s)</b> The SMTP client time limit for sending the SMTP DATA command, and for receiving the server response. <b><a href="postconf.5.html#smtp_data_xfer_timeout">smtp_data_xfer_timeout</a> (180s)</b> The SMTP client time limit for sending the SMTP message content. <b><a href="postconf.5.html#smtp_data_done_timeout">smtp_data_done_timeout</a> (600s)</b> The SMTP client time limit for sending the SMTP ".", and for receiving the server response. <b><a href="postconf.5.html#smtp_quit_timeout">smtp_quit_timeout</a> (300s)</b> The SMTP client time limit for sending the QUIT command, and for receiving the server response. Available in Postfix version 2.1 and later: <b><a href="postconf.5.html#smtp_mx_address_limit">smtp_mx_address_limit</a> (0)</b> The maximal number of MX (mail exchanger) IP addresses that can result from mail exchanger lookups, or zero (no limit). <b><a href="postconf.5.html#smtp_mx_session_limit">smtp_mx_session_limit</a> (2)</b> The maximal number of SMTP sessions per delivery request before giving up or delivering to a fall- back relay host, or zero (no limit). <b><a href="postconf.5.html#smtp_rset_timeout">smtp_rset_timeout</a> (120s)</b> The SMTP client time limit for sending the RSET command, and for receiving the server response. <b>TROUBLE SHOOTING CONTROLS</b> <b><a href="postconf.5.html#debug_peer_level">debug_peer_level</a> (2)</b> The increment in verbose logging level when a remote client or server matches a pattern in the <a href="postconf.5.html#debug_peer_list">debug_peer_list</a> parameter. <b><a href="postconf.5.html#debug_peer_list">debug_peer_list</a> (empty)</b> Optional list of remote client or server hostname or network address patterns that cause the verbose logging level to increase by the amount specified in $<a href="postconf.5.html#debug_peer_level">debug_peer_level</a>. <b><a href="postconf.5.html#error_notice_recipient">error_notice_recipient</a> (postmaster)</b> The recipient of postmaster notifications about mail delivery problems that are caused by policy, resource, software or protocol errors. <b><a href="postconf.5.html#notify_classes">notify_classes</a> (resource, software)</b> The list of error classes that are reported to the postmaster. <b>MISCELLANEOUS CONTROLS</b> <b><a href="postconf.5.html#best_mx_transport">best_mx_transport</a> (empty)</b> Where the Postfix SMTP client should deliver mail when it detects a "mail loops back to myself" error condition. <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b> The default location of the Postfix main.cf and master.cf configuration files. <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b> How much time a Postfix daemon process may take to handle a request before it is terminated by a built-in watchdog timer. <b><a href="postconf.5.html#disable_dns_lookups">disable_dns_lookups</a> (no)</b> Disable DNS lookups in the Postfix SMTP and LMTP clients. <b><a href="postconf.5.html#fallback_relay">fallback_relay</a> (empty)</b> Optional list of relay hosts for SMTP destinations that can't be found or that are unreachable. <b><a href="postconf.5.html#inet_interfaces">inet_interfaces</a> (all)</b> The network interface addresses that this mail sys- tem receives mail on. <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b> The time limit for sending or receiving information over an internal communication channel. <b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b> The maximum amount of time that an idle Postfix daemon process waits for the next service request before exiting. <b><a href="postconf.5.html#max_use">max_use</a> (100)</b> The maximal number of connection requests before a Postfix daemon process terminates. <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> The process ID of a Postfix command or daemon pro- cess. <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b> The process name of a Postfix command or daemon process. <b><a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a> (empty)</b> The network interface addresses that this mail sys- tem receives mail on by way of a proxy or network address translation unit. <b><a href="postconf.5.html#smtp_bind_address">smtp_bind_address</a> (empty)</b> An optional numerical network address that the SMTP client should bind to when making a connection. <b><a href="postconf.5.html#smtp_helo_name">smtp_helo_name</a> ($<a href="postconf.5.html#myhostname">myhostname</a>)</b> The hostname to send in the SMTP EHLO or HELO com- mand. <b><a href="postconf.5.html#smtp_host_lookup">smtp_host_lookup</a> (dns)</b> What mechanisms when the SMTP client uses to look up a host's IP address. <b><a href="postconf.5.html#smtp_randomize_addresses">smtp_randomize_addresses</a> (yes)</b> Randomize the order of equal-preference MX host addresses. <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> The syslog facility of Postfix logging. <b><a href="postconf.5.html#syslog_name">syslog_name</a> (postfix)</b> The mail system name that is prepended to the pro- cess name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd". <b>SEE ALSO</b> <a href="qmgr.8.html">qmgr(8)</a>, queue manager <a href="bounce.8.html">bounce(8)</a>, delivery status reports <a href="postconf.5.html">postconf(5)</a>, configuration parameters <a href="master.8.html">master(8)</a>, process manager syslogd(8), system logging <b>README FILES</b> <a href="SASL_README.html">SASL_README</a>, Postfix SASL howto <b>LICENSE</b> The Secure Mailer license must be distributed with this software. <b>AUTHOR(S)</b> Wietse Venema IBM T.J. Watson Research P.O. Box 704 Yorktown Heights, NY 10598, USA SMTP(8) </pre> </body> </html>