<!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 SMTP+LMTP client <b>SYNOPSIS</b> <b>smtp</b> [generic Postfix daemon options] <b>DESCRIPTION</b> The Postfix SMTP+LMTP client implements the SMTP and LMTP mail delivery protocols. It 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 recipient information. This program expects to be run from the <a href="master.8.html"><b>master</b>(8)</a> process manager. The SMTP+LMTP client updates the queue file and marks recipients 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+LMTP 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+LMTP client will try to deliver the mail to an alternate host. After a successful mail transaction, a connection may be saved to the <a href="scache.8.html"><b>scache</b>(8)</a> connection cache server, so that it may be used by any SMTP+LMTP client for a subsequent transaction. By default, connection caching is enabled temporarily for destinations that have a high volume of mail in the active queue. Connection caching can be enabled permanently for specific destinations. <b>SMTP DESTINATION SYNTAX</b> SMTP destinations have the following form: <i>domainname</i> <i>domainname</i>:<i>port</i> Look up the mail exchangers for the specified domain, and connect to the specified port (default: <b>smtp</b>). [<i>hostname</i>] [<i>hostname</i>]:<i>port</i> Look up the address(es) of the specified host, and connect to the specified port (default: <b>smtp</b>). [<i>address</i>] [<i>address</i>]:<i>port</i> Connect to the host at the specified address, and connect to the specified port (default: <b>smtp</b>). An IPv6 address must be formatted as [<b>ipv6</b>:<i>address</i>]. <b>LMTP DESTINATION SYNTAX</b> LMTP destinations have the following form: <b>unix</b>:<i>pathname</i> Connect to the local UNIX-domain server that is bound to the specified <i>pathname</i>. If the process runs chrooted, an absolute pathname is interpreted relative to the Postfix queue directory. <b>inet</b>:<i>hostname</i> <b>inet:</b><i>hostname</i>:<i>port</i> <b>inet</b>:[<i>address</i>] <b>inet</b>:[<i>address</i>]:<i>port</i> Connect to the specified TCP port on the specified local or remote host. If no port is specified, con- nect to the port defined as <b>lmtp</b> in <b>services</b>(4). If no such service is found, the <b><a href="postconf.5.html#lmtp_tcp_port">lmtp_tcp_port</a></b> con- figuration parameter (default value of 24) will be used. An IPv6 address must be formatted as [<b>ipv6</b>:<i>address</i>]. <b>SECURITY</b> The SMTP+LMTP client is moderately security-sensitive. It talks to SMTP or LMTP servers and to DNS servers on the network. The SMTP+LMTP client can be run chrooted at fixed low privilege. <b>STANDARDS</b> <a href="http://tools.ietf.org/html/rfc821">RFC 821</a> (SMTP protocol) <a href="http://tools.ietf.org/html/rfc822">RFC 822</a> (ARPA Internet Text Messages) <a href="http://tools.ietf.org/html/rfc1651">RFC 1651</a> (SMTP service extensions) <a href="http://tools.ietf.org/html/rfc1652">RFC 1652</a> (8bit-MIME transport) <a href="http://tools.ietf.org/html/rfc1870">RFC 1870</a> (Message Size Declaration) <a href="http://tools.ietf.org/html/rfc2033">RFC 2033</a> (LMTP protocol) <a href="http://tools.ietf.org/html/rfc2034">RFC 2034</a> (SMTP Enhanced Error Codes) <a href="http://tools.ietf.org/html/rfc2045">RFC 2045</a> (MIME: Format of Internet Message Bodies) <a href="http://tools.ietf.org/html/rfc2046">RFC 2046</a> (MIME: Media Types) <a href="http://tools.ietf.org/html/rfc2554">RFC 2554</a> (AUTH command) <a href="http://tools.ietf.org/html/rfc2821">RFC 2821</a> (SMTP protocol) <a href="http://tools.ietf.org/html/rfc2920">RFC 2920</a> (SMTP Pipelining) <a href="http://tools.ietf.org/html/rfc3207">RFC 3207</a> (STARTTLS command) <a href="http://tools.ietf.org/html/rfc3461">RFC 3461</a> (SMTP DSN Extension) <a href="http://tools.ietf.org/html/rfc3463">RFC 3463</a> (Enhanced Status Codes) <a href="http://tools.ietf.org/html/rfc4954">RFC 4954</a> (AUTH command) <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>BUGS</b> SMTP and LMTP connection caching does not work with TLS. The necessary support for TLS object passivation and re- activation does not exist without closing the session, which defeats the purpose. SMTP and LMTP connection caching assumes that SASL creden- tials are valid for all destinations that map onto the same IP address and TCP port. <b>CONFIGURATION PARAMETERS</b> Before Postfix version 2.3, the LMTP client is a separate program that implements only a subset of the functionality available with SMTP: there is no support for TLS, and con- nections are cached in-process, making it ineffective when the client is used for multiple domains. Most smtp_<i>xxx</i> configuration parameters have an lmtp_<i>xxx</i> "mirror" parameter for the equivalent LMTP feature. This document describes only those LMTP-related parameters that aren't simply "mirror" parameters. Changes to <a href="postconf.5.html"><b>main.cf</b></a> are picked up automatically, as <a href="smtp.8.html"><b>smtp</b>(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"><b>postconf</b>(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 Post- fix SMTP client turns on the PIX firewall "<CR><LF>.<CR><LF>" bug workaround for delivery through firewalls with "smtp fixup" mode turned on. <b><a href="postconf.5.html#smtp_pix_workarounds">smtp_pix_workarounds</a> (disable_esmtp, delay_dotcrlf)</b> A list that specifies zero or more workarounds for CISCO PIX firewall bugs. <b><a href="postconf.5.html#smtp_pix_workaround_maps">smtp_pix_workaround_maps</a> (empty)</b> Lookup tables, indexed by the remote SMTP server address, with per-destination workarounds for CISCO PIX firewall bugs. <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://tools.ietf.org/html/rfc2821">RFC 2821</a>. <b><a href="postconf.5.html#smtp_reply_filter">smtp_reply_filter</a> (empty)</b> A mechanism to transform replies from remote SMTP servers one line at a time. <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). Available in Postfix version 2.2 and later: <b><a href="postconf.5.html#smtp_discard_ehlo_keyword_address_maps">smtp_discard_ehlo_keyword_address_maps</a> (empty)</b> Lookup tables, indexed by the remote SMTP server address, with case insensitive lists of EHLO key- words (pipelining, starttls, auth, etc.) that the Postfix SMTP client will ignore in the EHLO response from a remote SMTP server. <b><a href="postconf.5.html#smtp_discard_ehlo_keywords">smtp_discard_ehlo_keywords</a> (empty)</b> A case insensitive list of EHLO keywords (pipelin- ing, starttls, auth, etc.) that the Postfix SMTP client will ignore in the EHLO response from a remote SMTP server. <b><a href="postconf.5.html#smtp_generic_maps">smtp_generic_maps</a> (empty)</b> Optional lookup tables that perform address rewrit- ing in the SMTP client, typically to transform a locally valid address into a globally valid address when sending mail across the Internet. Available in Postfix version 2.2.9 and later: <b><a href="postconf.5.html#smtp_cname_overrides_servername">smtp_cname_overrides_servername</a> (version dependent)</b> Allow DNS CNAME records to override the servername that the Postfix SMTP client uses for logging, SASL password lookup, TLS policy decisions, or TLS cer- tificate verification. Available in Postfix version 2.3 and later: <b><a href="postconf.5.html#lmtp_discard_lhlo_keyword_address_maps">lmtp_discard_lhlo_keyword_address_maps</a> (empty)</b> Lookup tables, indexed by the remote LMTP server address, with case insensitive lists of LHLO key- words (pipelining, starttls, auth, etc.) that the LMTP client will ignore in the LHLO response from a remote LMTP server. <b><a href="postconf.5.html#lmtp_discard_lhlo_keywords">lmtp_discard_lhlo_keywords</a> (empty)</b> A case insensitive list of LHLO keywords (pipelin- ing, starttls, auth, etc.) that the LMTP client will ignore in the LHLO response from a remote LMTP server. Available in Postfix version 2.4.4 and later: <b><a href="postconf.5.html#send_cyrus_sasl_authzid">send_cyrus_sasl_authzid</a> (no)</b> When authenticating to a remote SMTP or LMTP server with the default setting "no", send no SASL autho- riZation ID (authzid); send only the SASL authenti- Cation ID (authcid) plus the authcid's password. Available in Postfix version 2.5 and later: <b><a href="postconf.5.html#smtp_header_checks">smtp_header_checks</a> (empty)</b> Restricted <a href="header_checks.5.html"><b>header_checks</b>(5)</a> tables for the Postfix SMTP client. <b><a href="postconf.5.html#smtp_mime_header_checks">smtp_mime_header_checks</a> (empty)</b> Restricted <b><a href="postconf.5.html#mime_header_checks">mime_header_checks</a></b>(5) tables for the Postfix SMTP client. <b><a href="postconf.5.html#smtp_nested_header_checks">smtp_nested_header_checks</a> (empty)</b> Restricted <b><a href="postconf.5.html#nested_header_checks">nested_header_checks</a></b>(5) tables for the Postfix SMTP client. <b><a href="postconf.5.html#smtp_body_checks">smtp_body_checks</a> (empty)</b> Restricted <a href="header_checks.5.html"><b>body_checks</b>(5)</a> tables for the Postfix SMTP client. Available in Postfix version 2.6 and later: <b><a href="postconf.5.html#tcp_windowsize">tcp_windowsize</a> (0)</b> An optional workaround for routers that break TCP window scaling. Available in Postfix version 2.8 and later: <b><a href="postconf.5.html#smtp_dns_resolver_options">smtp_dns_resolver_options</a> (empty)</b> DNS Resolver options for the Postfix SMTP client. <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 recursion level 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, or sender address when sender-dependent authentica- tion is enabled. <b><a href="postconf.5.html#smtp_sasl_security_options">smtp_sasl_security_options</a> (noplaintext, noanonymous)</b> Postfix SMTP client SASL security options; as of Postfix 2.3 the list of available features depends on the SASL client implementation that is selected with <b><a href="postconf.5.html#smtp_sasl_type">smtp_sasl_type</a></b>. Available in Postfix version 2.2 and later: <b><a href="postconf.5.html#smtp_sasl_mechanism_filter">smtp_sasl_mechanism_filter</a> (empty)</b> If non-empty, a Postfix SMTP client filter for the remote SMTP server's list of offered SASL mecha- nisms. Available in Postfix version 2.3 and later: <b><a href="postconf.5.html#smtp_sender_dependent_authentication">smtp_sender_dependent_authentication</a> (no)</b> Enable sender-dependent authentication in the Post- fix SMTP client; this is available only with SASL authentication, and disables SMTP connection caching to ensure that mail from different senders will use the appropriate credentials. <b><a href="postconf.5.html#smtp_sasl_path">smtp_sasl_path</a> (empty)</b> Implementation-specific information that the Post- fix SMTP client passes through to the SASL plug-in implementation that is selected with <b><a href="postconf.5.html#smtp_sasl_type">smtp_sasl_type</a></b>. <b><a href="postconf.5.html#smtp_sasl_type">smtp_sasl_type</a> (cyrus)</b> The SASL plug-in type that the Postfix SMTP client should use for authentication. Available in Postfix version 2.5 and later: <b><a href="postconf.5.html#smtp_sasl_auth_cache_name">smtp_sasl_auth_cache_name</a> (empty)</b> An optional table to prevent repeated SASL authen- tication failures with the same remote SMTP server hostname, username and password. <b><a href="postconf.5.html#smtp_sasl_auth_cache_time">smtp_sasl_auth_cache_time</a> (90d)</b> The maximal age of an <a href="postconf.5.html#smtp_sasl_auth_cache_name">smtp_sasl_auth_cache_name</a> entry before it is removed. <b><a href="postconf.5.html#smtp_sasl_auth_soft_bounce">smtp_sasl_auth_soft_bounce</a> (yes)</b> When a remote SMTP server rejects a SASL authenti- cation request with a 535 reply code, defer mail delivery instead of returning mail as undeliver- able. <b>STARTTLS SUPPORT CONTROLS</b> Detailed information about STARTTLS configuration may be found in the <a href="TLS_README.html">TLS_README</a> document. <b><a href="postconf.5.html#smtp_tls_security_level">smtp_tls_security_level</a> (empty)</b> The default SMTP TLS security level for the Postfix SMTP client; when a non-empty value is specified, this overrides the obsolete parameters <a href="postconf.5.html#smtp_use_tls">smtp_use_tls</a>, <a href="postconf.5.html#smtp_enforce_tls">smtp_enforce_tls</a>, and <a href="postconf.5.html#smtp_tls_enforce_peername">smtp_tls_enforce_peername</a>. <b><a href="postconf.5.html#smtp_sasl_tls_security_options">smtp_sasl_tls_security_options</a> ($<a href="postconf.5.html#smtp_sasl_security_options">smtp_sasl_secu</a>-</b> <b><a href="postconf.5.html#smtp_sasl_security_options">rity_options</a>)</b> The SASL authentication security options that the Postfix SMTP client uses for TLS encrypted SMTP sessions. <b><a href="postconf.5.html#smtp_starttls_timeout">smtp_starttls_timeout</a> (300s)</b> Time limit for Postfix SMTP client write and read operations during TLS startup and shutdown hand- shake procedures. <b><a href="postconf.5.html#smtp_tls_CAfile">smtp_tls_CAfile</a> (empty)</b> A file containing CA certificates of root CAs trusted to sign either remote SMTP server certifi- cates or intermediate CA certificates. <b><a href="postconf.5.html#smtp_tls_CApath">smtp_tls_CApath</a> (empty)</b> Directory with PEM format certificate authority certificates that the Postfix SMTP client uses to verify a remote SMTP server certificate. <b><a href="postconf.5.html#smtp_tls_cert_file">smtp_tls_cert_file</a> (empty)</b> File with the Postfix SMTP client RSA certificate in PEM format. <b><a href="postconf.5.html#smtp_tls_mandatory_ciphers">smtp_tls_mandatory_ciphers</a> (medium)</b> The minimum TLS cipher grade that the Postfix SMTP client will use with mandatory TLS encryption. <b><a href="postconf.5.html#smtp_tls_exclude_ciphers">smtp_tls_exclude_ciphers</a> (empty)</b> List of ciphers or cipher types to exclude from the Postfix SMTP client cipher list at all TLS security levels. <b><a href="postconf.5.html#smtp_tls_mandatory_exclude_ciphers">smtp_tls_mandatory_exclude_ciphers</a> (empty)</b> Additional list of ciphers or cipher types to exclude from the SMTP client cipher list at manda- tory TLS security levels. <b><a href="postconf.5.html#smtp_tls_dcert_file">smtp_tls_dcert_file</a> (empty)</b> File with the Postfix SMTP client DSA certificate in PEM format. <b><a href="postconf.5.html#smtp_tls_dkey_file">smtp_tls_dkey_file</a> ($<a href="postconf.5.html#smtp_tls_dcert_file">smtp_tls_dcert_file</a>)</b> File with the Postfix SMTP client DSA private key in PEM format. <b><a href="postconf.5.html#smtp_tls_key_file">smtp_tls_key_file</a> ($<a href="postconf.5.html#smtp_tls_cert_file">smtp_tls_cert_file</a>)</b> File with the Postfix SMTP client RSA private key in PEM format. <b><a href="postconf.5.html#smtp_tls_loglevel">smtp_tls_loglevel</a> (0)</b> Enable additional Postfix SMTP client logging of TLS activity. <b><a href="postconf.5.html#smtp_tls_note_starttls_offer">smtp_tls_note_starttls_offer</a> (no)</b> Log the hostname of a remote SMTP server that offers STARTTLS, when TLS is not already enabled for that server. <b><a href="postconf.5.html#smtp_tls_policy_maps">smtp_tls_policy_maps</a> (empty)</b> Optional lookup tables with the Postfix SMTP client TLS security policy by next-hop destination; when a non-empty value is specified, this overrides the obsolete <a href="postconf.5.html#smtp_tls_per_site">smtp_tls_per_site</a> parameter. <b><a href="postconf.5.html#smtp_tls_mandatory_protocols">smtp_tls_mandatory_protocols</a> (SSLv3, TLSv1)</b> List of SSL/TLS protocols that the Postfix SMTP client will use with mandatory TLS encryption. <b><a href="postconf.5.html#smtp_tls_scert_verifydepth">smtp_tls_scert_verifydepth</a> (9)</b> The verification depth for remote SMTP server cer- tificates. <b><a href="postconf.5.html#smtp_tls_secure_cert_match">smtp_tls_secure_cert_match</a> (nexthop, dot-nexthop)</b> The server certificate peername verification method for the "secure" TLS security level. <b><a href="postconf.5.html#smtp_tls_session_cache_database">smtp_tls_session_cache_database</a> (empty)</b> Name of the file containing the optional Postfix SMTP client TLS session cache. <b><a href="postconf.5.html#smtp_tls_session_cache_timeout">smtp_tls_session_cache_timeout</a> (3600s)</b> The expiration time of Postfix SMTP client TLS ses- sion cache information. <b><a href="postconf.5.html#smtp_tls_verify_cert_match">smtp_tls_verify_cert_match</a> (hostname)</b> The server certificate peername verification method for the "verify" TLS security level. <b><a href="postconf.5.html#tls_daemon_random_bytes">tls_daemon_random_bytes</a> (32)</b> The number of pseudo-random bytes that an <a href="smtp.8.html"><b>smtp</b>(8)</a> or <a href="smtpd.8.html"><b>smtpd</b>(8)</a> process requests from the <a href="tlsmgr.8.html"><b>tlsmgr</b>(8)</a> server in order to seed its internal pseudo random number generator (PRNG). <b><a href="postconf.5.html#tls_high_cipherlist">tls_high_cipherlist</a></b> <b>(ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)</b> The OpenSSL cipherlist for "HIGH" grade ciphers. <b><a href="postconf.5.html#tls_medium_cipherlist">tls_medium_cipherlist</a> (ALL:!EXPORT:!LOW:+RC4:@STRENGTH)</b> The OpenSSL cipherlist for "MEDIUM" or higher grade ciphers. <b><a href="postconf.5.html#tls_low_cipherlist">tls_low_cipherlist</a> (ALL:!EXPORT:+RC4:@STRENGTH)</b> The OpenSSL cipherlist for "LOW" or higher grade ciphers. <b><a href="postconf.5.html#tls_export_cipherlist">tls_export_cipherlist</a> (ALL:+RC4:@STRENGTH)</b> The OpenSSL cipherlist for "EXPORT" or higher grade ciphers. <b><a href="postconf.5.html#tls_null_cipherlist">tls_null_cipherlist</a> (eNULL:!aNULL)</b> The OpenSSL cipherlist for "NULL" grade ciphers that provide authentication without encryption. Available in Postfix version 2.4 and later: <b><a href="postconf.5.html#smtp_sasl_tls_verified_security_options">smtp_sasl_tls_verified_security_options</a></b> <b>($<a href="postconf.5.html#smtp_sasl_tls_security_options">smtp_sasl_tls_security_options</a>)</b> The SASL authentication security options that the Postfix SMTP client uses for TLS encrypted SMTP sessions with a verified server certificate. Available in Postfix version 2.5 and later: <b><a href="postconf.5.html#smtp_tls_fingerprint_cert_match">smtp_tls_fingerprint_cert_match</a> (empty)</b> List of acceptable remote SMTP server certificate fingerprints for the "fingerprint" TLS security level (<b><a href="postconf.5.html#smtp_tls_security_level">smtp_tls_security_level</a></b> = fingerprint). <b><a href="postconf.5.html#smtp_tls_fingerprint_digest">smtp_tls_fingerprint_digest</a> (md5)</b> The message digest algorithm used to construct remote SMTP server certificate fingerprints. Available in Postfix version 2.6 and later: <b><a href="postconf.5.html#smtp_tls_protocols">smtp_tls_protocols</a> (!SSLv2)</b> List of TLS protocols that the Postfix SMTP client will exclude or include with opportunistic TLS encryption. <b><a href="postconf.5.html#smtp_tls_ciphers">smtp_tls_ciphers</a> (export)</b> The minimum TLS cipher grade that the Postfix SMTP client will use with opportunistic TLS encryption. <b><a href="postconf.5.html#smtp_tls_eccert_file">smtp_tls_eccert_file</a> (empty)</b> File with the Postfix SMTP client ECDSA certificate in PEM format. <b><a href="postconf.5.html#smtp_tls_eckey_file">smtp_tls_eckey_file</a> ($<a href="postconf.5.html#smtp_tls_eccert_file">smtp_tls_eccert_file</a>)</b> File with the Postfix SMTP client ECDSA private key in PEM format. Available in Postfix version 2.7 and later: <b><a href="postconf.5.html#smtp_tls_block_early_mail_reply">smtp_tls_block_early_mail_reply</a> (no)</b> Try to detect a mail hijacking attack based on a TLS protocol vulnerability (CVE-2009-3555), where an attacker prepends malicious HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client TLS session. Available in Postfix version 2.8 and later: <b><a href="postconf.5.html#tls_disable_workarounds">tls_disable_workarounds</a> (see 'postconf -d' output)</b> List or bit-mask of OpenSSL bug work-arounds to disable. <b>OBSOLETE STARTTLS CONTROLS</b> The following configuration parameters exist for compati- bility with Postfix versions before 2.3. Support for these will be removed in a future release. <b><a href="postconf.5.html#smtp_use_tls">smtp_use_tls</a> (no)</b> Opportunistic mode: use TLS when a remote SMTP server announces STARTTLS support, otherwise send the mail in the clear. <b><a href="postconf.5.html#smtp_enforce_tls">smtp_enforce_tls</a> (no)</b> Enforcement mode: require that remote SMTP servers use TLS encryption, and never send mail in the clear. <b><a href="postconf.5.html#smtp_tls_enforce_peername">smtp_tls_enforce_peername</a> (yes)</b> With mandatory TLS encryption, require that the remote SMTP server hostname matches the information in the remote SMTP server certificate. <b><a href="postconf.5.html#smtp_tls_per_site">smtp_tls_per_site</a> (empty)</b> Optional lookup tables with the Postfix SMTP client TLS usage policy by next-hop destination and by remote SMTP server hostname. <b><a href="postconf.5.html#smtp_tls_cipherlist">smtp_tls_cipherlist</a> (empty)</b> Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS cipher list. <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 message for 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#lmtp_lhlo_timeout">lmtp_lhlo_timeout</a> (300s)</b> The LMTP client time limit for sending the LHLO 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> (5)</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 <a href="postconf.5.html#relayhost">relay host</a>, or zero (no limit). <b><a href="postconf.5.html#smtp_rset_timeout">smtp_rset_timeout</a> (20s)</b> The SMTP client time limit for sending the RSET command, and for receiving the server response. Available in Postfix version 2.2 and earlier: <b><a href="postconf.5.html#lmtp_cache_connection">lmtp_cache_connection</a> (yes)</b> Keep Postfix LMTP client connections open for up to $<a href="postconf.5.html#max_idle">max_idle</a> seconds. Available in Postfix version 2.2 and later: <b><a href="postconf.5.html#smtp_connection_cache_destinations">smtp_connection_cache_destinations</a> (empty)</b> Permanently enable SMTP connection caching for the specified destinations. <b><a href="postconf.5.html#smtp_connection_cache_on_demand">smtp_connection_cache_on_demand</a> (yes)</b> Temporarily enable SMTP connection caching while a destination has a high volume of mail in the active queue. <b><a href="postconf.5.html#smtp_connection_reuse_time_limit">smtp_connection_reuse_time_limit</a> (300s)</b> The amount of time during which Postfix will use an SMTP connection repeatedly. <b><a href="postconf.5.html#smtp_connection_cache_time_limit">smtp_connection_cache_time_limit</a> (2s)</b> When SMTP connection caching is enabled, the amount of time that an unused SMTP client socket is kept open before it is closed. Available in Postfix version 2.3 and later: <b><a href="postconf.5.html#connection_cache_protocol_timeout">connection_cache_protocol_timeout</a> (5s)</b> Time limit for connection cache connect, send or receive operations. <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#internal_mail_filter_classes">internal_mail_filter_classes</a> (empty)</b> What categories of Postfix-generated mail are sub- ject to before-queue content inspection by <a href="postconf.5.html#non_smtpd_milters">non_smtpd_milters</a>, <a href="postconf.5.html#header_checks">header_checks</a> and <a href="postconf.5.html#body_checks">body_checks</a>. <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 <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> 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#delay_logging_resolution_limit">delay_logging_resolution_limit</a> (2)</b> The maximal number of digits after the decimal point when logging sub-second delay values. <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#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#inet_protocols">inet_protocols</a> (ipv4)</b> The Internet protocols Postfix will attempt to use when making or accepting connections. <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#lmtp_assume_final">lmtp_assume_final</a> (no)</b> When an LMTP server announces no DSN support, assume that the server performs final delivery, and send "delivered" delivery status notifications instead of "relayed". <b><a href="postconf.5.html#lmtp_tcp_port">lmtp_tcp_port</a> (24)</b> The default TCP port that the Postfix LMTP client connects to. <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 an incoming connection before terminating voluntarily. <b><a href="postconf.5.html#max_use">max_use</a> (100)</b> The maximal number of incoming connections that a Postfix daemon process will service before termi- nating voluntarily. <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> The process ID of a Postfix command or daemon process. <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_address_preference">smtp_address_preference</a> (ipv6)</b> The address type ("ipv6", "ipv4" or "any") that the Postfix SMTP client will try first, when a destina- tion has IPv6 and IPv4 addresses with equal MX preference. <b><a href="postconf.5.html#smtp_bind_address">smtp_bind_address</a> (empty)</b> An optional numerical network address that the Postfix SMTP client should bind to when making an IPv4 connection. <b><a href="postconf.5.html#smtp_bind_address6">smtp_bind_address6</a> (empty)</b> An optional numerical network address that the Postfix SMTP client should bind to when making an IPv6 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#lmtp_lhlo_name">lmtp_lhlo_name</a> ($<a href="postconf.5.html#myhostname">myhostname</a>)</b> The hostname to send in the LMTP LHLO command. <b><a href="postconf.5.html#smtp_host_lookup">smtp_host_lookup</a> (dns)</b> What mechanisms the Postfix SMTP client uses to look up a host's IP address. <b><a href="postconf.5.html#smtp_randomize_addresses">smtp_randomize_addresses</a> (yes)</b> Randomize the order of equal-preference MX host addresses. <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> The syslog facility of Postfix logging. <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b> The mail system name that is prepended to the process name in syslog records, so that "smtpd" becomes, for example, "postfix/smtpd". Available with Postfix 2.2 and earlier: <b><a href="postconf.5.html#fallback_relay">fallback_relay</a> (empty)</b> Optional list of relay hosts for SMTP destinations that can't be found or that are unreachable. Available with Postfix 2.3 and later: <b><a href="postconf.5.html#smtp_fallback_relay">smtp_fallback_relay</a> ($<a href="postconf.5.html#fallback_relay">fallback_relay</a>)</b> Optional list of relay hosts for SMTP destinations that can't be found or that are unreachable. <b>SEE ALSO</b> <a href="generic.5.html">generic(5)</a>, output address rewriting <a href="header_checks.5.html">header_checks(5)</a>, message header content inspection <a href="header_checks.5.html">body_checks(5)</a>, body parts content inspection <a href="qmgr.8.html">qmgr(8)</a>, queue manager <a href="bounce.8.html">bounce(8)</a>, delivery status reports <a href="scache.8.html">scache(8)</a>, connection cache server <a href="postconf.5.html">postconf(5)</a>, configuration parameters <a href="master.5.html">master(5)</a>, generic daemon options <a href="master.8.html">master(8)</a>, process manager <a href="tlsmgr.8.html">tlsmgr(8)</a>, TLS session and PRNG management syslogd(8), system logging <b>README FILES</b> <a href="SASL_README.html">SASL_README</a>, Postfix SASL howto <a href="TLS_README.html">TLS_README</a>, Postfix STARTTLS 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 Command pipelining in cooperation with: Jon Ribbens Oaktree Internet Solutions Ltd., Internet House, Canal Basin, Coventry, CV1 4LY, United Kingdom. SASL support originally by: Till Franke SuSE Rhein/Main AG 65760 Eschborn, Germany TLS support originally by: Lutz Jaenicke BTU Cottbus Allgemeine Elektrotechnik Universitaetsplatz 3-4 D-03044 Cottbus, Germany Revised TLS and SMTP connection cache support by: Victor Duchovni Morgan Stanley SMTP(8) </pre> </body> </html>