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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> (998)</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 Postfix SMTP client MAIL FROM
and RCPT TO commands 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 remote SMTP servers that greet with a 5XX sta-
tus 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 Postfix SMTP client, typically to trans-
form 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
Postfix 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 Postfix 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.
Available in Postfix version 2.9 and later:
<b><a href="postconf.5.html#smtp_per_record_deadline">smtp_per_record_deadline</a> (no)</b>
Change the behavior of the smtp_*_timeout time lim-
its, from a time limit per read or write system
call, to a time limit to send or receive a complete
record (an SMTP command line, SMTP response line,
SMTP message content line, or TLS protocol mes-
sage).
<b><a href="postconf.5.html#smtp_send_dummy_mail_auth">smtp_send_dummy_mail_auth</a> (no)</b>
Whether or not to append the "AUTH=<>" option to
the MAIL FROM command in SASL-authenticated SMTP
sessions.
<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 Postfix SMTP client lookup tables with one
username:password entry per remote hostname or
domain, or sender address when sender-dependent
authentication 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.
Available in Postfix version 2.9 and later:
<b><a href="postconf.5.html#smtp_send_dummy_mail_auth">smtp_send_dummy_mail_auth</a> (no)</b>
Whether or not to append the "AUTH=<>" option to
the MAIL FROM command in SASL-authenticated SMTP
sessions.
<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> ($<a href="postconf.5.html#smtp_sasl_security_options">smtp_sasl_secu</a>-</b>
<b><a href="postconf.5.html#smtp_sasl_security_options">rity_options</a>)</b>
The SASL authentication security options that the
Postfix SMTP client uses for TLS encrypted SMTP
sessions.
<b><a href="postconf.5.html#smtp_starttls_timeout">smtp_starttls_timeout</a> (300s)</b>
Time limit for Postfix SMTP client write and read
operations during TLS startup and shutdown hand-
shake procedures.
<b><a href="postconf.5.html#smtp_tls_CAfile">smtp_tls_CAfile</a> (empty)</b>
A file containing CA certificates of root CAs
trusted to sign either remote SMTP server certifi-
cates or intermediate CA certificates.
<b><a href="postconf.5.html#smtp_tls_CApath">smtp_tls_CApath</a> (empty)</b>
Directory with PEM format certificate authority
certificates that the Postfix SMTP client uses to
verify a remote SMTP server certificate.
<b><a href="postconf.5.html#smtp_tls_cert_file">smtp_tls_cert_file</a> (empty)</b>
File with the Postfix SMTP client RSA certificate
in PEM format.
<b><a href="postconf.5.html#smtp_tls_mandatory_ciphers">smtp_tls_mandatory_ciphers</a> (medium)</b>
The minimum TLS cipher grade that the Postfix SMTP
client will use with mandatory TLS encryption.
<b><a href="postconf.5.html#smtp_tls_exclude_ciphers">smtp_tls_exclude_ciphers</a> (empty)</b>
List of ciphers or cipher types to exclude from the
Postfix SMTP client cipher list at all TLS security
levels.
<b><a href="postconf.5.html#smtp_tls_mandatory_exclude_ciphers">smtp_tls_mandatory_exclude_ciphers</a> (empty)</b>
Additional list of ciphers or cipher types to
exclude from the Postfix SMTP client cipher list at
mandatory TLS security levels.
<b><a href="postconf.5.html#smtp_tls_dcert_file">smtp_tls_dcert_file</a> (empty)</b>
File with the Postfix SMTP client DSA certificate
in PEM format.
<b><a href="postconf.5.html#smtp_tls_dkey_file">smtp_tls_dkey_file</a> ($<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> (!SSLv2)</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>
How the Postfix SMTP client verifies the server
certificate peername 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>
How the Postfix SMTP client verifies the server
certificate peername 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 Postfix 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 Postfix SMTP client time limit for sending the
HELO or EHLO command, and for receiving the initial
remote SMTP server response.
<b><a href="postconf.5.html#lmtp_lhlo_timeout">lmtp_lhlo_timeout</a> (300s)</b>
The Postfix LMTP client time limit for sending the
LHLO command, and for receiving the initial remote
LMTP server response.
<b><a href="postconf.5.html#smtp_xforward_timeout">smtp_xforward_timeout</a> (300s)</b>
The Postfix SMTP client time limit for sending the
XFORWARD command, and for receiving the remote SMTP
server response.
<b><a href="postconf.5.html#smtp_mail_timeout">smtp_mail_timeout</a> (300s)</b>
The Postfix SMTP client time limit for sending the
MAIL FROM command, and for receiving the remote
SMTP server response.
<b><a href="postconf.5.html#smtp_rcpt_timeout">smtp_rcpt_timeout</a> (300s)</b>
The Postfix SMTP client time limit for sending the
SMTP RCPT TO command, and for receiving the remote
SMTP server response.
<b><a href="postconf.5.html#smtp_data_init_timeout">smtp_data_init_timeout</a> (120s)</b>
The Postfix SMTP client time limit for sending the
SMTP DATA command, and for receiving the remote
SMTP server response.
<b><a href="postconf.5.html#smtp_data_xfer_timeout">smtp_data_xfer_timeout</a> (180s)</b>
The Postfix 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 Postfix SMTP client time limit for sending the
SMTP ".", and for receiving the remote SMTP server
response.
<b><a href="postconf.5.html#smtp_quit_timeout">smtp_quit_timeout</a> (300s)</b>
The Postfix SMTP client time limit for sending the
QUIT command, and for receiving the remote SMTP
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 Postfix SMTP client
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 the Postfix SMTP client gives up or
delivers 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 Postfix SMTP client time limit for sending the
RSET command, and for receiving the remote SMTP
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.
Available in Postfix version 2.9 and later:
<b><a href="postconf.5.html#smtp_per_record_deadline">smtp_per_record_deadline</a> (no)</b>
Change the behavior of the smtp_*_timeout time lim-
its, from a time limit per read or write system
call, to a time limit to send or receive a complete
record (an SMTP command line, SMTP response line,
SMTP message content line, or TLS protocol mes-
sage).
<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> (all)</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 a remote 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> (any)</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>
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