/*++ /* NAME /* smtp 8 /* SUMMARY /* Postfix SMTP+LMTP client /* SYNOPSIS /* \fBsmtp\fR [generic Postfix daemon options] /* DESCRIPTION /* 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 \fBmaster\fR(8) 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 \fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) 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 \fBscache\fR(8) 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. /* SMTP DESTINATION SYNTAX /* .ad /* .fi /* SMTP destinations have the following form: /* .IP \fIdomainname\fR /* .IP \fIdomainname\fR:\fIport\fR /* Look up the mail exchangers for the specified domain, and /* connect to the specified port (default: \fBsmtp\fR). /* .IP [\fIhostname\fR] /* .IP [\fIhostname\fR]:\fIport\fR /* Look up the address(es) of the specified host, and connect to /* the specified port (default: \fBsmtp\fR). /* .IP [\fIaddress\fR] /* .IP [\fIaddress\fR]:\fIport\fR /* Connect to the host at the specified address, and connect /* to the specified port (default: \fBsmtp\fR). An IPv6 address /* must be formatted as [\fBipv6\fR:\fIaddress\fR]. /* LMTP DESTINATION SYNTAX /* .ad /* .fi /* LMTP destinations have the following form: /* .IP \fBunix\fR:\fIpathname\fR /* Connect to the local UNIX-domain server that is bound to the specified /* \fIpathname\fR. If the process runs chrooted, an absolute pathname /* is interpreted relative to the Postfix queue directory. /* .IP \fBinet\fR:\fIhostname\fR /* .IP \fBinet\fB:\fIhostname\fR:\fIport\fR /* .IP \fBinet\fR:[\fIaddress\fR] /* .IP \fBinet\fR:[\fIaddress\fR]:\fIport\fR /* Connect to the specified TCP port on the specified local or /* remote host. If no port is specified, connect to the port defined as /* \fBlmtp\fR in \fBservices\fR(4). /* If no such service is found, the \fBlmtp_tcp_port\fR configuration /* parameter (default value of 24) will be used. /* An IPv6 address must be formatted as [\fBipv6\fR:\fIaddress\fR]. /* .PP /* SECURITY /* .ad /* .fi /* 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. /* STANDARDS /* RFC 821 (SMTP protocol) /* RFC 822 (ARPA Internet Text Messages) /* RFC 1651 (SMTP service extensions) /* RFC 1652 (8bit-MIME transport) /* RFC 1870 (Message Size Declaration) /* RFC 2033 (LMTP protocol) /* RFC 2034 (SMTP Enhanced Error Codes) /* RFC 2045 (MIME: Format of Internet Message Bodies) /* RFC 2046 (MIME: Media Types) /* RFC 2554 (AUTH command) /* RFC 2821 (SMTP protocol) /* RFC 2920 (SMTP Pipelining) /* RFC 3207 (STARTTLS command) /* RFC 3461 (SMTP DSN Extension) /* RFC 3463 (Enhanced Status Codes) /* RFC 4954 (AUTH command) /* DIAGNOSTICS /* Problems and transactions are logged to \fBsyslogd\fR(8). /* Corrupted message files are marked so that the queue manager can /* move them to the \fBcorrupt\fR queue for further inspection. /* /* Depending on the setting of the \fBnotify_classes\fR parameter, /* the postmaster is notified of bounces, protocol problems, and of /* other trouble. /* BUGS /* 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 credentials /* are valid for all destinations that map onto the same IP /* address and TCP port. /* CONFIGURATION PARAMETERS /* .ad /* .fi /* 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 /* connections are cached in-process, making it ineffective /* when the client is used for multiple domains. /* /* Most smtp_\fIxxx\fR configuration parameters have an /* lmtp_\fIxxx\fR "mirror" parameter for the equivalent LMTP /* feature. This document describes only those LMTP-related /* parameters that aren't simply "mirror" parameters. /* /* Changes to \fBmain.cf\fR are picked up automatically, as \fBsmtp\fR(8) /* processes run for only a limited amount of time. Use the command /* "\fBpostfix reload\fR" to speed up a change. /* /* The text below provides only a parameter summary. See /* \fBpostconf\fR(5) for more details including examples. /* COMPATIBILITY CONTROLS /* .ad /* .fi /* .IP "\fBignore_mx_lookup_error (no)\fR" /* Ignore DNS MX lookups that produce no response. /* .IP "\fBsmtp_always_send_ehlo (yes)\fR" /* Always send EHLO at the start of an SMTP session. /* .IP "\fBsmtp_never_send_ehlo (no)\fR" /* Never send EHLO at the start of an SMTP session. /* .IP "\fBsmtp_defer_if_no_mx_address_found (no)\fR" /* Defer mail delivery when no MX record resolves to an IP address. /* .IP "\fBsmtp_line_length_limit (990)\fR" /* The maximal length of message header and body lines that Postfix /* will send via SMTP. /* .IP "\fBsmtp_pix_workaround_delay_time (10s)\fR" /* How long the Postfix SMTP client pauses before sending /* ".<CR><LF>" in order to work around the PIX firewall /* "<CR><LF>.<CR><LF>" bug. /* .IP "\fBsmtp_pix_workaround_threshold_time (500s)\fR" /* How long a message must be queued before the Postfix SMTP client /* turns on the PIX firewall "<CR><LF>.<CR><LF>" /* bug workaround for delivery through firewalls with "smtp fixup" /* mode turned on. /* .IP "\fBsmtp_pix_workarounds (disable_esmtp, delay_dotcrlf)\fR" /* A list that specifies zero or more workarounds for CISCO PIX /* firewall bugs. /* .IP "\fBsmtp_pix_workaround_maps (empty)\fR" /* Lookup tables, indexed by the remote SMTP server address, with /* per-destination workarounds for CISCO PIX firewall bugs. /* .IP "\fBsmtp_quote_rfc821_envelope (yes)\fR" /* Quote addresses in SMTP MAIL FROM and RCPT TO commands as required /* by RFC 2821. /* .IP "\fBsmtp_reply_filter (empty)\fR" /* A mechanism to transform replies from remote SMTP servers one /* line at a time. /* .IP "\fBsmtp_skip_5xx_greeting (yes)\fR" /* Skip SMTP servers that greet with a 5XX status code (go away, do /* not try again later). /* .IP "\fBsmtp_skip_quit_response (yes)\fR" /* Do not wait for the response to the SMTP QUIT command. /* .PP /* Available in Postfix version 2.0 and earlier: /* .IP "\fBsmtp_skip_4xx_greeting (yes)\fR" /* Skip SMTP servers that greet with a 4XX status code (go away, try /* again later). /* .PP /* Available in Postfix version 2.2 and later: /* .IP "\fBsmtp_discard_ehlo_keyword_address_maps (empty)\fR" /* Lookup tables, indexed by the remote SMTP server address, with /* case insensitive lists of EHLO keywords (pipelining, starttls, auth, /* etc.) that the Postfix SMTP client will ignore in the EHLO response from a /* remote SMTP server. /* .IP "\fBsmtp_discard_ehlo_keywords (empty)\fR" /* A case insensitive list of EHLO keywords (pipelining, starttls, /* auth, etc.) that the Postfix SMTP client will ignore in the EHLO /* response from a remote SMTP server. /* .IP "\fBsmtp_generic_maps (empty)\fR" /* Optional lookup tables that perform address rewriting in the /* SMTP client, typically to transform a locally valid address into /* a globally valid address when sending mail across the Internet. /* .PP /* Available in Postfix version 2.2.9 and later: /* .IP "\fBsmtp_cname_overrides_servername (version dependent)\fR" /* Allow DNS CNAME records to override the servername that the /* Postfix SMTP client uses for logging, SASL password lookup, TLS /* policy decisions, or TLS certificate verification. /* .PP /* Available in Postfix version 2.3 and later: /* .IP "\fBlmtp_discard_lhlo_keyword_address_maps (empty)\fR" /* Lookup tables, indexed by the remote LMTP server address, with /* case insensitive lists of LHLO keywords (pipelining, starttls, /* auth, etc.) that the LMTP client will ignore in the LHLO response /* from a remote LMTP server. /* .IP "\fBlmtp_discard_lhlo_keywords (empty)\fR" /* A case insensitive list of LHLO keywords (pipelining, starttls, /* auth, etc.) that the LMTP client will ignore in the LHLO response /* from a remote LMTP server. /* .PP /* Available in Postfix version 2.4.4 and later: /* .IP "\fBsend_cyrus_sasl_authzid (no)\fR" /* When authenticating to a remote SMTP or LMTP server with the /* default setting "no", send no SASL authoriZation ID (authzid); send /* only the SASL authentiCation ID (authcid) plus the authcid's password. /* .PP /* Available in Postfix version 2.5 and later: /* .IP "\fBsmtp_header_checks (empty)\fR" /* Restricted \fBheader_checks\fR(5) tables for the Postfix SMTP client. /* .IP "\fBsmtp_mime_header_checks (empty)\fR" /* Restricted \fBmime_header_checks\fR(5) tables for the Postfix SMTP /* client. /* .IP "\fBsmtp_nested_header_checks (empty)\fR" /* Restricted \fBnested_header_checks\fR(5) tables for the Postfix SMTP /* client. /* .IP "\fBsmtp_body_checks (empty)\fR" /* Restricted \fBbody_checks\fR(5) tables for the Postfix SMTP client. /* .PP /* Available in Postfix version 2.6 and later: /* .IP "\fBtcp_windowsize (0)\fR" /* An optional workaround for routers that break TCP window scaling. /* .PP /* Available in Postfix version 2.8 and later: /* .IP "\fBsmtp_dns_resolver_options (empty)\fR" /* DNS Resolver options for the Postfix SMTP client. /* MIME PROCESSING CONTROLS /* .ad /* .fi /* Available in Postfix version 2.0 and later: /* .IP "\fBdisable_mime_output_conversion (no)\fR" /* Disable the conversion of 8BITMIME format to 7BIT format. /* .IP "\fBmime_boundary_length_limit (2048)\fR" /* The maximal length of MIME multipart boundary strings. /* .IP "\fBmime_nesting_limit (100)\fR" /* The maximal recursion level that the MIME processor will handle. /* EXTERNAL CONTENT INSPECTION CONTROLS /* .ad /* .fi /* Available in Postfix version 2.1 and later: /* .IP "\fBsmtp_send_xforward_command (no)\fR" /* Send the non-standard XFORWARD command when the Postfix SMTP server /* EHLO response announces XFORWARD support. /* SASL AUTHENTICATION CONTROLS /* .ad /* .fi /* .IP "\fBsmtp_sasl_auth_enable (no)\fR" /* Enable SASL authentication in the Postfix SMTP client. /* .IP "\fBsmtp_sasl_password_maps (empty)\fR" /* Optional SMTP client lookup tables with one username:password entry /* per remote hostname or domain, or sender address when sender-dependent /* authentication is enabled. /* .IP "\fBsmtp_sasl_security_options (noplaintext, noanonymous)\fR" /* 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 \fBsmtp_sasl_type\fR. /* .PP /* Available in Postfix version 2.2 and later: /* .IP "\fBsmtp_sasl_mechanism_filter (empty)\fR" /* If non-empty, a Postfix SMTP client filter for the remote SMTP /* server's list of offered SASL mechanisms. /* .PP /* Available in Postfix version 2.3 and later: /* .IP "\fBsmtp_sender_dependent_authentication (no)\fR" /* Enable sender-dependent authentication in the Postfix 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. /* .IP "\fBsmtp_sasl_path (empty)\fR" /* Implementation-specific information that the Postfix SMTP client /* passes through to /* the SASL plug-in implementation that is selected with /* \fBsmtp_sasl_type\fR. /* .IP "\fBsmtp_sasl_type (cyrus)\fR" /* The SASL plug-in type that the Postfix SMTP client should use /* for authentication. /* .PP /* Available in Postfix version 2.5 and later: /* .IP "\fBsmtp_sasl_auth_cache_name (empty)\fR" /* An optional table to prevent repeated SASL authentication /* failures with the same remote SMTP server hostname, username and /* password. /* .IP "\fBsmtp_sasl_auth_cache_time (90d)\fR" /* The maximal age of an smtp_sasl_auth_cache_name entry before it /* is removed. /* .IP "\fBsmtp_sasl_auth_soft_bounce (yes)\fR" /* When a remote SMTP server rejects a SASL authentication request /* with a 535 reply code, defer mail delivery instead of returning /* mail as undeliverable. /* STARTTLS SUPPORT CONTROLS /* .ad /* .fi /* Detailed information about STARTTLS configuration may be found /* in the TLS_README document. /* .IP "\fBsmtp_tls_security_level (empty)\fR" /* The default SMTP TLS security level for the Postfix SMTP client; /* when a non-empty value is specified, this overrides the obsolete /* parameters smtp_use_tls, smtp_enforce_tls, and smtp_tls_enforce_peername. /* .IP "\fBsmtp_sasl_tls_security_options ($smtp_sasl_security_options)\fR" /* The SASL authentication security options that the Postfix SMTP /* client uses for TLS encrypted SMTP sessions. /* .IP "\fBsmtp_starttls_timeout (300s)\fR" /* Time limit for Postfix SMTP client write and read operations /* during TLS startup and shutdown handshake procedures. /* .IP "\fBsmtp_tls_CAfile (empty)\fR" /* A file containing CA certificates of root CAs trusted to sign /* either remote SMTP server certificates or intermediate CA certificates. /* .IP "\fBsmtp_tls_CApath (empty)\fR" /* Directory with PEM format certificate authority certificates /* that the Postfix SMTP client uses to verify a remote SMTP server /* certificate. /* .IP "\fBsmtp_tls_cert_file (empty)\fR" /* File with the Postfix SMTP client RSA certificate in PEM format. /* .IP "\fBsmtp_tls_mandatory_ciphers (medium)\fR" /* The minimum TLS cipher grade that the Postfix SMTP client will /* use with /* mandatory TLS encryption. /* .IP "\fBsmtp_tls_exclude_ciphers (empty)\fR" /* List of ciphers or cipher types to exclude from the Postfix /* SMTP client cipher /* list at all TLS security levels. /* .IP "\fBsmtp_tls_mandatory_exclude_ciphers (empty)\fR" /* Additional list of ciphers or cipher types to exclude from the /* SMTP client cipher list at mandatory TLS security levels. /* .IP "\fBsmtp_tls_dcert_file (empty)\fR" /* File with the Postfix SMTP client DSA certificate in PEM format. /* .IP "\fBsmtp_tls_dkey_file ($smtp_tls_dcert_file)\fR" /* File with the Postfix SMTP client DSA private key in PEM format. /* .IP "\fBsmtp_tls_key_file ($smtp_tls_cert_file)\fR" /* File with the Postfix SMTP client RSA private key in PEM format. /* .IP "\fBsmtp_tls_loglevel (0)\fR" /* Enable additional Postfix SMTP client logging of TLS activity. /* .IP "\fBsmtp_tls_note_starttls_offer (no)\fR" /* Log the hostname of a remote SMTP server that offers STARTTLS, /* when TLS is not already enabled for that server. /* .IP "\fBsmtp_tls_policy_maps (empty)\fR" /* 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 smtp_tls_per_site parameter. /* .IP "\fBsmtp_tls_mandatory_protocols (SSLv3, TLSv1)\fR" /* List of SSL/TLS protocols that the Postfix SMTP client will use with /* mandatory TLS encryption. /* .IP "\fBsmtp_tls_scert_verifydepth (9)\fR" /* The verification depth for remote SMTP server certificates. /* .IP "\fBsmtp_tls_secure_cert_match (nexthop, dot-nexthop)\fR" /* The server certificate peername verification method for the /* "secure" TLS security level. /* .IP "\fBsmtp_tls_session_cache_database (empty)\fR" /* Name of the file containing the optional Postfix SMTP client /* TLS session cache. /* .IP "\fBsmtp_tls_session_cache_timeout (3600s)\fR" /* The expiration time of Postfix SMTP client TLS session cache /* information. /* .IP "\fBsmtp_tls_verify_cert_match (hostname)\fR" /* The server certificate peername verification method for the /* "verify" TLS security level. /* .IP "\fBtls_daemon_random_bytes (32)\fR" /* The number of pseudo-random bytes that an \fBsmtp\fR(8) or \fBsmtpd\fR(8) /* process requests from the \fBtlsmgr\fR(8) server in order to seed its /* internal pseudo random number generator (PRNG). /* .IP "\fBtls_high_cipherlist (ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)\fR" /* The OpenSSL cipherlist for "HIGH" grade ciphers. /* .IP "\fBtls_medium_cipherlist (ALL:!EXPORT:!LOW:+RC4:@STRENGTH)\fR" /* The OpenSSL cipherlist for "MEDIUM" or higher grade ciphers. /* .IP "\fBtls_low_cipherlist (ALL:!EXPORT:+RC4:@STRENGTH)\fR" /* The OpenSSL cipherlist for "LOW" or higher grade ciphers. /* .IP "\fBtls_export_cipherlist (ALL:+RC4:@STRENGTH)\fR" /* The OpenSSL cipherlist for "EXPORT" or higher grade ciphers. /* .IP "\fBtls_null_cipherlist (eNULL:!aNULL)\fR" /* The OpenSSL cipherlist for "NULL" grade ciphers that provide /* authentication without encryption. /* .PP /* Available in Postfix version 2.4 and later: /* .IP "\fBsmtp_sasl_tls_verified_security_options ($smtp_sasl_tls_security_options)\fR" /* The SASL authentication security options that the Postfix SMTP /* client uses for TLS encrypted SMTP sessions with a verified server /* certificate. /* .PP /* Available in Postfix version 2.5 and later: /* .IP "\fBsmtp_tls_fingerprint_cert_match (empty)\fR" /* List of acceptable remote SMTP server certificate fingerprints /* for the "fingerprint" TLS security level (\fBsmtp_tls_security_level\fR = /* fingerprint). /* .IP "\fBsmtp_tls_fingerprint_digest (md5)\fR" /* The message digest algorithm used to construct remote SMTP server /* certificate fingerprints. /* .PP /* Available in Postfix version 2.6 and later: /* .IP "\fBsmtp_tls_protocols (!SSLv2)\fR" /* List of TLS protocols that the Postfix SMTP client will exclude or /* include with opportunistic TLS encryption. /* .IP "\fBsmtp_tls_ciphers (export)\fR" /* The minimum TLS cipher grade that the Postfix SMTP client /* will use with opportunistic TLS encryption. /* .IP "\fBsmtp_tls_eccert_file (empty)\fR" /* File with the Postfix SMTP client ECDSA certificate in PEM format. /* .IP "\fBsmtp_tls_eckey_file ($smtp_tls_eccert_file)\fR" /* File with the Postfix SMTP client ECDSA private key in PEM format. /* .PP /* Available in Postfix version 2.7 and later: /* .IP "\fBsmtp_tls_block_early_mail_reply (no)\fR" /* Try to detect a mail hijacking attack based on a TLS protocol /* vulnerability (CVE-2009-3555), where an attacker prepends malicious /* HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client TLS session. /* .PP /* Available in Postfix version 2.8 and later: /* .IP "\fBtls_disable_workarounds (see 'postconf -d' output)\fR" /* List or bit-mask of OpenSSL bug work-arounds to disable. /* OBSOLETE STARTTLS CONTROLS /* .ad /* .fi /* The following configuration parameters exist for compatibility /* with Postfix versions before 2.3. Support for these will /* be removed in a future release. /* .IP "\fBsmtp_use_tls (no)\fR" /* Opportunistic mode: use TLS when a remote SMTP server announces /* STARTTLS support, otherwise send the mail in the clear. /* .IP "\fBsmtp_enforce_tls (no)\fR" /* Enforcement mode: require that remote SMTP servers use TLS /* encryption, and never send mail in the clear. /* .IP "\fBsmtp_tls_enforce_peername (yes)\fR" /* With mandatory TLS encryption, require that the remote SMTP /* server hostname matches the information in the remote SMTP server /* certificate. /* .IP "\fBsmtp_tls_per_site (empty)\fR" /* Optional lookup tables with the Postfix SMTP client TLS usage /* policy by next-hop destination and by remote SMTP server hostname. /* .IP "\fBsmtp_tls_cipherlist (empty)\fR" /* Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS /* cipher list. /* RESOURCE AND RATE CONTROLS /* .ad /* .fi /* .IP "\fBsmtp_destination_concurrency_limit ($default_destination_concurrency_limit)\fR" /* The maximal number of parallel deliveries to the same destination /* via the smtp message delivery transport. /* .IP "\fBsmtp_destination_recipient_limit ($default_destination_recipient_limit)\fR" /* The maximal number of recipients per message for the smtp /* message delivery transport. /* .IP "\fBsmtp_connect_timeout (30s)\fR" /* The SMTP client time limit for completing a TCP connection, or /* zero (use the operating system built-in time limit). /* .IP "\fBsmtp_helo_timeout (300s)\fR" /* The SMTP client time limit for sending the HELO or EHLO command, /* and for receiving the initial server response. /* .IP "\fBlmtp_lhlo_timeout (300s)\fR" /* The LMTP client time limit for sending the LHLO command, and /* for receiving the initial server response. /* .IP "\fBsmtp_xforward_timeout (300s)\fR" /* The SMTP client time limit for sending the XFORWARD command, and /* for receiving the server response. /* .IP "\fBsmtp_mail_timeout (300s)\fR" /* The SMTP client time limit for sending the MAIL FROM command, and /* for receiving the server response. /* .IP "\fBsmtp_rcpt_timeout (300s)\fR" /* The SMTP client time limit for sending the SMTP RCPT TO command, and /* for receiving the server response. /* .IP "\fBsmtp_data_init_timeout (120s)\fR" /* The SMTP client time limit for sending the SMTP DATA command, and for /* receiving the server response. /* .IP "\fBsmtp_data_xfer_timeout (180s)\fR" /* The SMTP client time limit for sending the SMTP message content. /* .IP "\fBsmtp_data_done_timeout (600s)\fR" /* The SMTP client time limit for sending the SMTP ".", and for receiving /* the server response. /* .IP "\fBsmtp_quit_timeout (300s)\fR" /* The SMTP client time limit for sending the QUIT command, and for /* receiving the server response. /* .PP /* Available in Postfix version 2.1 and later: /* .IP "\fBsmtp_mx_address_limit (5)\fR" /* The maximal number of MX (mail exchanger) IP addresses that can /* result from mail exchanger lookups, or zero (no limit). /* .IP "\fBsmtp_mx_session_limit (2)\fR" /* The maximal number of SMTP sessions per delivery request before /* giving up or delivering to a fall-back relay host, or zero (no /* limit). /* .IP "\fBsmtp_rset_timeout (20s)\fR" /* The SMTP client time limit for sending the RSET command, and /* for receiving the server response. /* .PP /* Available in Postfix version 2.2 and earlier: /* .IP "\fBlmtp_cache_connection (yes)\fR" /* Keep Postfix LMTP client connections open for up to $max_idle /* seconds. /* .PP /* Available in Postfix version 2.2 and later: /* .IP "\fBsmtp_connection_cache_destinations (empty)\fR" /* Permanently enable SMTP connection caching for the specified /* destinations. /* .IP "\fBsmtp_connection_cache_on_demand (yes)\fR" /* Temporarily enable SMTP connection caching while a destination /* has a high volume of mail in the active queue. /* .IP "\fBsmtp_connection_reuse_time_limit (300s)\fR" /* The amount of time during which Postfix will use an SMTP /* connection repeatedly. /* .IP "\fBsmtp_connection_cache_time_limit (2s)\fR" /* When SMTP connection caching is enabled, the amount of time that /* an unused SMTP client socket is kept open before it is closed. /* .PP /* Available in Postfix version 2.3 and later: /* .IP "\fBconnection_cache_protocol_timeout (5s)\fR" /* Time limit for connection cache connect, send or receive /* operations. /* TROUBLE SHOOTING CONTROLS /* .ad /* .fi /* .IP "\fBdebug_peer_level (2)\fR" /* The increment in verbose logging level when a remote client or /* server matches a pattern in the debug_peer_list parameter. /* .IP "\fBdebug_peer_list (empty)\fR" /* 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 $debug_peer_level. /* .IP "\fBerror_notice_recipient (postmaster)\fR" /* The recipient of postmaster notifications about mail delivery /* problems that are caused by policy, resource, software or protocol /* errors. /* .IP "\fBinternal_mail_filter_classes (empty)\fR" /* What categories of Postfix-generated mail are subject to /* before-queue content inspection by non_smtpd_milters, header_checks /* and body_checks. /* .IP "\fBnotify_classes (resource, software)\fR" /* The list of error classes that are reported to the postmaster. /* MISCELLANEOUS CONTROLS /* .ad /* .fi /* .IP "\fBbest_mx_transport (empty)\fR" /* Where the Postfix SMTP client should deliver mail when it detects /* a "mail loops back to myself" error condition. /* .IP "\fBconfig_directory (see 'postconf -d' output)\fR" /* The default location of the Postfix main.cf and master.cf /* configuration files. /* .IP "\fBdaemon_timeout (18000s)\fR" /* How much time a Postfix daemon process may take to handle a /* request before it is terminated by a built-in watchdog timer. /* .IP "\fBdelay_logging_resolution_limit (2)\fR" /* The maximal number of digits after the decimal point when logging /* sub-second delay values. /* .IP "\fBdisable_dns_lookups (no)\fR" /* Disable DNS lookups in the Postfix SMTP and LMTP clients. /* .IP "\fBinet_interfaces (all)\fR" /* The network interface addresses that this mail system receives /* mail on. /* .IP "\fBinet_protocols (ipv4)\fR" /* The Internet protocols Postfix will attempt to use when making /* or accepting connections. /* .IP "\fBipc_timeout (3600s)\fR" /* The time limit for sending or receiving information over an internal /* communication channel. /* .IP "\fBlmtp_assume_final (no)\fR" /* When an LMTP server announces no DSN support, assume that the /* server performs final delivery, and send "delivered" delivery status /* notifications instead of "relayed". /* .IP "\fBlmtp_tcp_port (24)\fR" /* The default TCP port that the Postfix LMTP client connects to. /* .IP "\fBmax_idle (100s)\fR" /* The maximum amount of time that an idle Postfix daemon process waits /* for an incoming connection before terminating voluntarily. /* .IP "\fBmax_use (100)\fR" /* The maximal number of incoming connections that a Postfix daemon /* process will service before terminating voluntarily. /* .IP "\fBprocess_id (read-only)\fR" /* The process ID of a Postfix command or daemon process. /* .IP "\fBprocess_name (read-only)\fR" /* The process name of a Postfix command or daemon process. /* .IP "\fBproxy_interfaces (empty)\fR" /* The network interface addresses that this mail system receives mail /* on by way of a proxy or network address translation unit. /* .IP "\fBsmtp_address_preference (ipv6)\fR" /* The address type ("ipv6", "ipv4" or "any") that the Postfix /* SMTP client will try first, when a destination has IPv6 and IPv4 /* addresses with equal MX preference. /* .IP "\fBsmtp_bind_address (empty)\fR" /* An optional numerical network address that the Postfix SMTP client /* should bind to when making an IPv4 connection. /* .IP "\fBsmtp_bind_address6 (empty)\fR" /* An optional numerical network address that the Postfix SMTP client /* should bind to when making an IPv6 connection. /* .IP "\fBsmtp_helo_name ($myhostname)\fR" /* The hostname to send in the SMTP EHLO or HELO command. /* .IP "\fBlmtp_lhlo_name ($myhostname)\fR" /* The hostname to send in the LMTP LHLO command. /* .IP "\fBsmtp_host_lookup (dns)\fR" /* What mechanisms the Postfix SMTP client uses to look up a host's IP /* address. /* .IP "\fBsmtp_randomize_addresses (yes)\fR" /* Randomize the order of equal-preference MX host addresses. /* .IP "\fBsyslog_facility (mail)\fR" /* The syslog facility of Postfix logging. /* .IP "\fBsyslog_name (see 'postconf -d' output)\fR" /* The mail system name that is prepended to the process name in syslog /* records, so that "smtpd" becomes, for example, "postfix/smtpd". /* .PP /* Available with Postfix 2.2 and earlier: /* .IP "\fBfallback_relay (empty)\fR" /* Optional list of relay hosts for SMTP destinations that can't be /* found or that are unreachable. /* .PP /* Available with Postfix 2.3 and later: /* .IP "\fBsmtp_fallback_relay ($fallback_relay)\fR" /* Optional list of relay hosts for SMTP destinations that can't be /* found or that are unreachable. /* SEE ALSO /* generic(5), output address rewriting /* header_checks(5), message header content inspection /* body_checks(5), body parts content inspection /* qmgr(8), queue manager /* bounce(8), delivery status reports /* scache(8), connection cache server /* postconf(5), configuration parameters /* master(5), generic daemon options /* master(8), process manager /* tlsmgr(8), TLS session and PRNG management /* syslogd(8), system logging /* README FILES /* .ad /* .fi /* Use "\fBpostconf readme_directory\fR" or /* "\fBpostconf html_directory\fR" to locate this information. /* .na /* .nf /* SASL_README, Postfix SASL howto /* TLS_README, Postfix STARTTLS howto /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* 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 /*--*/ /* System library. */ #include <sys_defs.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <dict.h> #include <stringops.h> /* Utility library. */ #include <msg.h> #include <mymalloc.h> #include <name_mask.h> #include <name_code.h> /* Global library. */ #include <deliver_request.h> #include <mail_params.h> #include <mail_version.h> #include <mail_conf.h> #include <debug_peer.h> #include <flush_clnt.h> #include <scache.h> #include <string_list.h> #include <maps.h> #include <ext_prop.h> /* DNS library. */ #include <dns.h> /* Single server skeleton. */ #include <mail_server.h> /* Application-specific. */ #include "smtp.h" #include "smtp_sasl.h" /* * Tunable parameters. These have compiled-in defaults that can be overruled * by settings in the global Postfix configuration file. */ int var_smtp_conn_tmout; int var_smtp_helo_tmout; int var_smtp_xfwd_tmout; int var_smtp_mail_tmout; int var_smtp_rcpt_tmout; int var_smtp_data0_tmout; int var_smtp_data1_tmout; int var_smtp_data2_tmout; int var_smtp_rset_tmout; int var_smtp_quit_tmout; char *var_inet_interfaces; char *var_notify_classes; int var_smtp_skip_5xx_greeting; int var_ign_mx_lookup_err; int var_skip_quit_resp; char *var_fallback_relay; char *var_bestmx_transp; char *var_error_rcpt; int var_smtp_always_ehlo; int var_smtp_never_ehlo; char *var_smtp_sasl_opts; char *var_smtp_sasl_path; char *var_smtp_sasl_passwd; bool var_smtp_sasl_enable; char *var_smtp_sasl_mechs; char *var_smtp_sasl_type; char *var_smtp_bind_addr; char *var_smtp_bind_addr6; bool var_smtp_rand_addr; int var_smtp_pix_thresh; int var_smtp_pix_delay; int var_smtp_line_limit; char *var_smtp_helo_name; char *var_smtp_host_lookup; bool var_smtp_quote_821_env; bool var_smtp_defer_mxaddr; bool var_smtp_send_xforward; int var_smtp_mxaddr_limit; int var_smtp_mxsess_limit; int var_smtp_cache_conn; int var_smtp_reuse_time; char *var_smtp_cache_dest; char *var_scache_service; /* You can now leave this here. */ bool var_smtp_cache_demand; char *var_smtp_ehlo_dis_words; char *var_smtp_ehlo_dis_maps; char *var_smtp_addr_pref; char *var_smtp_tls_level; bool var_smtp_use_tls; bool var_smtp_enforce_tls; char *var_smtp_tls_per_site; char *var_smtp_tls_policy; #ifdef USE_TLS char *var_smtp_sasl_tls_opts; char *var_smtp_sasl_tlsv_opts; int var_smtp_starttls_tmout; char *var_smtp_tls_CAfile; char *var_smtp_tls_CApath; char *var_smtp_tls_cert_file; char *var_smtp_tls_mand_ciph; char *var_smtp_tls_excl_ciph; char *var_smtp_tls_mand_excl; char *var_smtp_tls_dcert_file; char *var_smtp_tls_dkey_file; bool var_smtp_tls_enforce_peername; char *var_smtp_tls_key_file; int var_smtp_tls_loglevel; bool var_smtp_tls_note_starttls_offer; char *var_smtp_tls_mand_proto; char *var_smtp_tls_sec_cmatch; int var_smtp_tls_scert_vd; char *var_smtp_tls_vfy_cmatch; char *var_smtp_tls_fpt_cmatch; char *var_smtp_tls_fpt_dgst; char *var_smtp_tls_proto; char *var_smtp_tls_ciph; char *var_smtp_tls_eccert_file; char *var_smtp_tls_eckey_file; bool var_smtp_tls_blk_early_mail_reply; #endif char *var_smtp_generic_maps; char *var_prop_extension; bool var_smtp_sender_auth; char *var_lmtp_tcp_port; int var_scache_proto_tmout; bool var_smtp_cname_overr; char *var_smtp_pix_bug_words; char *var_smtp_pix_bug_maps; char *var_cyrus_conf_path; char *var_smtp_head_chks; char *var_smtp_mime_chks; char *var_smtp_nest_chks; char *var_smtp_body_chks; char *var_smtp_resp_filter; bool var_lmtp_assume_final; char *var_smtp_dns_res_opt; /* Special handling of 535 AUTH errors. */ char *var_smtp_sasl_auth_cache_name; int var_smtp_sasl_auth_cache_time; bool var_smtp_sasl_auth_soft_bounce; /* * Global variables. */ int smtp_host_lookup_mask; STRING_LIST *smtp_cache_dest; SCACHE *smtp_scache; MAPS *smtp_ehlo_dis_maps; MAPS *smtp_generic_maps; int smtp_ext_prop_mask; unsigned smtp_dns_res_opt; MAPS *smtp_pix_bug_maps; HBC_CHECKS *smtp_header_checks; /* limited header checks */ HBC_CHECKS *smtp_body_checks; /* limited body checks */ #ifdef USE_TLS /* * OpenSSL client state (opaque handle) */ TLS_APPL_STATE *smtp_tls_ctx; #endif /* * IPv6 preference. */ static int smtp_addr_pref; /* deliver_message - deliver message with extreme prejudice */ static int deliver_message(const char *service, DELIVER_REQUEST *request) { SMTP_STATE *state; int result; if (msg_verbose) msg_info("deliver_message: from %s", request->sender); /* * Sanity checks. The smtp server is unprivileged and chrooted, so we can * afford to distribute the data censoring code, instead of having it all * in one place. */ if (request->nexthop[0] == 0) msg_fatal("empty nexthop hostname"); if (request->rcpt_list.len <= 0) msg_fatal("recipient count: %d", request->rcpt_list.len); /* * Initialize. Bundle all information about the delivery request, so that * we can produce understandable diagnostics when something goes wrong * many levels below. The alternative would be to make everything global. */ state = smtp_state_alloc(); state->request = request; state->src = request->fp; state->service = service; state->misc_flags |= smtp_addr_pref; SMTP_RCPT_INIT(state); /* * Establish an SMTP session and deliver this message to all requested * recipients. At the end, notify the postmaster of any protocol errors. * Optionally deliver mail locally when this machine is the best mail * exchanger. */ result = smtp_connect(state); /* * Clean up. */ smtp_state_free(state); return (result); } /* smtp_service - perform service for client */ static void smtp_service(VSTREAM *client_stream, char *service, char **argv) { DELIVER_REQUEST *request; int status; /* * Sanity check. This service takes no command-line arguments. */ if (argv[0]) msg_fatal("unexpected command-line argument: %s", argv[0]); /* * This routine runs whenever a client connects to the UNIX-domain socket * dedicated to remote SMTP delivery service. What we see below is a * little protocol to (1) tell the queue manager that we are ready, (2) * read a request from the queue manager, and (3) report the completion * status of that request. All connection-management stuff is handled by * the common code in single_server.c. */ if ((request = deliver_request_read(client_stream)) != 0) { status = deliver_message(service, request); deliver_request_done(client_stream, request, status); } } /* post_init - post-jail initialization */ static void post_init(char *unused_name, char **unused_argv) { static const NAME_MASK lookup_masks[] = { SMTP_HOST_LOOKUP_DNS, SMTP_HOST_FLAG_DNS, SMTP_HOST_LOOKUP_NATIVE, SMTP_HOST_FLAG_NATIVE, 0, }; static const NAME_MASK dns_res_opt_masks[] = { SMTP_DNS_RES_OPT_DEFNAMES, RES_DEFNAMES, SMTP_DNS_RES_OPT_DNSRCH, RES_DNSRCH, 0, }; /* * Select hostname lookup mechanisms. */ if (var_disable_dns) smtp_host_lookup_mask = SMTP_HOST_FLAG_NATIVE; else smtp_host_lookup_mask = name_mask(VAR_SMTP_HOST_LOOKUP, lookup_masks, var_smtp_host_lookup); if (msg_verbose) msg_info("host name lookup methods: %s", str_name_mask(VAR_SMTP_HOST_LOOKUP, lookup_masks, smtp_host_lookup_mask)); /* * Session cache instance. */ if (*var_smtp_cache_dest || var_smtp_cache_demand) #if 0 smtp_scache = scache_multi_create(); #else smtp_scache = scache_clnt_create(var_scache_service, var_scache_proto_tmout, var_ipc_idle_limit, var_ipc_ttl_limit); #endif /* * Select DNS query flags. */ smtp_dns_res_opt = name_mask(VAR_SMTP_DNS_RES_OPT, dns_res_opt_masks, var_smtp_dns_res_opt); } /* pre_init - pre-jail initialization */ static void pre_init(char *unused_name, char **unused_argv) { int use_tls; static const NAME_CODE addr_pref_map[] = { INET_PROTO_NAME_IPV6, SMTP_MISC_FLAG_PREF_IPV6, INET_PROTO_NAME_IPV4, SMTP_MISC_FLAG_PREF_IPV4, INET_PROTO_NAME_ANY, 0, 0, -1, }; /* * Turn on per-peer debugging. */ debug_peer_init(); /* * SASL initialization. */ if (var_smtp_sasl_enable) #ifdef USE_SASL_AUTH smtp_sasl_initialize(); #else msg_warn("%s is true, but SASL support is not compiled in", VAR_SMTP_SASL_ENABLE); #endif if (*var_smtp_tls_level != 0) switch (tls_level_lookup(var_smtp_tls_level)) { case TLS_LEV_SECURE: case TLS_LEV_VERIFY: case TLS_LEV_FPRINT: case TLS_LEV_ENCRYPT: var_smtp_use_tls = var_smtp_enforce_tls = 1; break; case TLS_LEV_MAY: var_smtp_use_tls = 1; var_smtp_enforce_tls = 0; break; case TLS_LEV_NONE: var_smtp_use_tls = var_smtp_enforce_tls = 0; break; default: /* tls_level_lookup() logs no warning. */ /* session_tls_init() assumes that var_smtp_tls_level is sane. */ msg_fatal("Invalid TLS level \"%s\"", var_smtp_tls_level); } use_tls = (var_smtp_use_tls || var_smtp_enforce_tls); /* * Initialize the TLS data before entering the chroot jail */ if (use_tls || var_smtp_tls_per_site[0] || var_smtp_tls_policy[0]) { #ifdef USE_TLS TLS_CLIENT_INIT_PROPS props; /* * We get stronger type safety and a cleaner interface by combining * the various parameters into a single tls_client_props structure. * * Large parameter lists are error-prone, so we emulate a language * feature that C does not have natively: named parameter lists. */ smtp_tls_ctx = TLS_CLIENT_INIT(&props, log_level = var_smtp_tls_loglevel, verifydepth = var_smtp_tls_scert_vd, cache_type = strcmp(var_procname, "smtp") == 0 ? TLS_MGR_SCACHE_SMTP : TLS_MGR_SCACHE_LMTP, cert_file = var_smtp_tls_cert_file, key_file = var_smtp_tls_key_file, dcert_file = var_smtp_tls_dcert_file, dkey_file = var_smtp_tls_dkey_file, eccert_file = var_smtp_tls_eccert_file, eckey_file = var_smtp_tls_eckey_file, CAfile = var_smtp_tls_CAfile, CApath = var_smtp_tls_CApath, fpt_dgst = var_smtp_tls_fpt_dgst); smtp_tls_list_init(); #else msg_warn("TLS has been selected, but TLS support is not compiled in"); #endif } /* * Flush client. */ flush_init(); /* * Session cache domain list. */ if (*var_smtp_cache_dest) smtp_cache_dest = string_list_init(MATCH_FLAG_NONE, var_smtp_cache_dest); /* * EHLO keyword filter. */ if (*var_smtp_ehlo_dis_maps) smtp_ehlo_dis_maps = maps_create(VAR_SMTP_EHLO_DIS_MAPS, var_smtp_ehlo_dis_maps, DICT_FLAG_LOCK); /* * PIX bug workarounds. */ if (*var_smtp_pix_bug_maps) smtp_pix_bug_maps = maps_create(VAR_SMTP_PIX_BUG_MAPS, var_smtp_pix_bug_maps, DICT_FLAG_LOCK); /* * Generic maps. */ if (*var_prop_extension) smtp_ext_prop_mask = ext_prop_mask(VAR_PROP_EXTENSION, var_prop_extension); if (*var_smtp_generic_maps) smtp_generic_maps = maps_create(VAR_SMTP_GENERIC_MAPS, var_smtp_generic_maps, DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX); /* * Header/body checks. */ smtp_header_checks = hbc_header_checks_create( VAR_SMTP_HEAD_CHKS, var_smtp_head_chks, VAR_SMTP_MIME_CHKS, var_smtp_mime_chks, VAR_SMTP_NEST_CHKS, var_smtp_nest_chks, smtp_hbc_callbacks); smtp_body_checks = hbc_body_checks_create( VAR_SMTP_BODY_CHKS, var_smtp_body_chks, smtp_hbc_callbacks); /* * Server reply filter. */ if (*var_smtp_resp_filter) smtp_chat_resp_filter = dict_open(var_smtp_resp_filter, O_RDONLY, DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX); /* * Address family preference. */ if (*var_smtp_addr_pref) { smtp_addr_pref = name_code(addr_pref_map, NAME_CODE_FLAG_NONE, var_smtp_addr_pref); if (smtp_addr_pref < 0) msg_fatal("bad %s value: %s", VAR_SMTP_ADDR_PREF, var_smtp_addr_pref); } } /* pre_accept - see if tables have changed */ static void pre_accept(char *unused_name, char **unused_argv) { const char *table; if ((table = dict_changed_name()) != 0) { msg_info("table %s has changed -- restarting", table); exit(0); } } MAIL_VERSION_STAMP_DECLARE; /* main - pass control to the single-threaded skeleton */ int main(int argc, char **argv) { #include "smtp_params.c" #include "lmtp_params.c" int smtp_mode; /* * Fingerprint executables and core dumps. */ MAIL_VERSION_STAMP_ALLOCATE; /* * XXX At this point, var_procname etc. are not initialized. */ smtp_mode = (strcmp(sane_basename((VSTRING *) 0, argv[0]), "smtp") == 0); /* * Initialize with the LMTP or SMTP parameter name space. */ single_server_main(argc, argv, smtp_service, MAIL_SERVER_TIME_TABLE, smtp_mode ? smtp_time_table : lmtp_time_table, MAIL_SERVER_INT_TABLE, smtp_mode ? smtp_int_table : lmtp_int_table, MAIL_SERVER_STR_TABLE, smtp_mode ? smtp_str_table : lmtp_str_table, MAIL_SERVER_BOOL_TABLE, smtp_mode ? smtp_bool_table : lmtp_bool_table, MAIL_SERVER_PRE_INIT, pre_init, MAIL_SERVER_POST_INIT, post_init, MAIL_SERVER_PRE_ACCEPT, pre_accept, 0); }