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SMTPD.CONF(5) File Formats Manual SMTPD.CONF(5) NAME smtpd.conf -- SMTP daemon configuration file DESCRIPTION smtpd.conf is the configuration file for the mail daemon smtpd(8). When mail arrives, each "RCPT TO:" command generates a mail envelope. If an envelope matches any of a pre-designated set of criteria (using the match directive), the message is accepted for delivery. A copy of the message, as well as its associated envelopes, is saved in the mail queue and later dispatched according to an associated set of actions (using the action directive). If an envelope does not match any op- tions, it is rejected. The match rules are evaluated sequentially, with the first match winning. The format of the configuration file is fairly flexible. The current line can be extended over multiple lines using a backslash (`\'). Com- ments can be put anywhere in the file using a hash mark (`#'), and ex- tend to the end of the current line. Care should be taken when com- menting out multi-line text: the comment is effective until the end of the entire block. Argument names not beginning with a letter, digit, or underscore, as well as reserved words (such as listen, match, and port), must be quoted. Arguments containing whitespace should be sur- rounded by double quotes ("). Macros can be defined that are later expanded in context. Macro names must start with a letter, digit, or underscore, and may contain any of those characters, but may not be reserved words. Macros are not ex- panded inside quotes. For example: lan_addr = "192.168.0.1" listen on $lan_addr listen on $lan_addr tls auth The syntax of smtpd.conf is described below. action name method [options] When the queue runner processes an envelope from the mail queue, it carries out the action name, selected by the match ... action directive when the message was received. The action directive provides configuration data for delivery attempts. Required lookups are performed at the time of each delivery at- tempt. Consequently, changing an action directive or the files it references and restarting the smtpd(8) daemon causes the changes to take effect for subsequent delivery attempts for the respective dispatcher name, even for messages that were already stuck in the queue prior to the configuration changes. The delivery method parameter may be one of the following: expand-only Only accept the message if a delivery method was speci- fied in an aliases or .forward file. forward-only Only accept the message if the recipient results in a remote address after the processing of aliases or for- ward file. lmtp destination [rcpt-to] Deliver the message to an LMTP server at destination. The location may be expressed as host:port or as a UNIX socket. Optionally, rcpt-to might be specified to use the re- cipient email address (after expansion) instead of the local user in the LMTP session as RCPT TO. maildir [pathname] [junk] Deliver the message to the maildir in pathname if spec- ified, or by default to ~/Maildir. The pathname may contain format specifiers that are ex- panded before use (see "FORMAT SPECIFIERS"). If the junk argument is provided, the message will be moved to the `Junk' folder if it contains a positive `X-Spam' header. This folder will be created under pathname if it does not yet exist. mbox Deliver the message to the user's mbox with mail.local(8). mda command Delegate the delivery to a command that receives the message on its standard input (see "MDA COMMANDS"). The command may contain format specifiers that are ex- panded before use (see "FORMAT SPECIFIERS"). relay Relay the message to another SMTP server. The local delivery methods support additional options: alias <table> Use the mapping table for aliases(5) expansion. ttl n{s|m|h|d} Specify how long a message may remain in the queue. user username Specify the username for performing the delivery, to be looked up with getpwnam(3). This is used for virtual hosting where a single user- name is in charge of handling delivery for all virtual users. This option is not usable with the mbox delivery method. Only the delivery user's .forward file will be processed. userbase <table> Use the mapping table for user lookups instead of the getpwnam(3) function. The userbase does not apply to the user option. virtual <table> Use the mapping table for virtual expansion. The aliasing table format is described in table(5). wrapper name Use the wrapper specified in mda wrapper. The relay delivery methods also support additional options: backup Operate as a backup mail exchanger delivering messages to any mail exchanger with higher priority. backup mx name Operate as a backup mail exchanger delivering messages to any mail exchanger with higher priority than mail exchanger identified as name. ca caname For secure connections, use the certificate authority associated with caname (declared in a ca directive) to validate the server's identity. helo heloname Advertise heloname as the hostname to other mail ex- changers during the HELO phase. helo-src <table> Use the mapping table to look up a hostname matching the source address, to advertise during the HELO phase. domain <domains> Do not perform MX lookups but look up destination do- main in domains and use matching relay url as relay host. host relay-url Do not perform MX lookups but relay messages to the re- lay host described by relay-url. The format for relay-url is [proto://[label@]]host[:port]. The fol- lowing protocols are available: smtp Normal SMTP session with opportunistic STARTTLS (the default). smtp+tls Normal SMTP session with mandatory START- TLS. smtp+notls Plain text SMTP session without TLS. lmtp LMTP session. port is required. smtps SMTP session with forced TLS on connection. The default port is 465. Unless noted, port defaults to 25. The label corresponds to an entry in a credentials ta- ble, as documented in table(5). It is used with the "smtp+tls" and "smtps" protocols for authentication. Server certificates for those protocols are verified by default. pki pkiname For secure connections, use the certificate associated with pkiname (declared in a pki directive) to prove the client's identity to the remote mail server. srs When relaying a mail resulting from a forward, use the Sender Rewriting Scheme to rewrite sender address. tls [no-verify] Require TLS to be used when relaying, using mandatory STARTTLS by default. When used with a smarthost, the protocol must not be "smtp+notls://". If no-verify is specified, do not require a valid certificate. protocols protostr Define the protocol versions to be used for TLS ses- sions. Refer to the tls_config_parse_protocols(3) man- page for the format of protostr. ciphers cipherstr Define the list of ciphers that may be used for TLS sessions. Refer to the tls_config_set_ciphers(3) man- page for the format of cipherstr. auth <table> Use the mapping table for connecting to relay-url using credentials. This option is usable only with host op- tion. The credential table format is described in table(5). mail-from mailaddr Use mailaddr as the MAIL FROM address within the SMTP transaction. src sourceaddr | <sourceaddr> Use the string or list table sourceaddr for the source IP address, which is useful on machines with multiple interfaces. If the list contains more than one ad- dress, all of them are used in such a way that traffic is routed as efficiently as possible. admd authservid The Administrative Management Domain this mail server belongs to. The authservid will be forwarded to filters using it to identify or mark authentication-results headers. If omitted, it defaults to the server name. bounce warn-interval delay [, delay ...] Send warning messages to the envelope sender when temporary de- livery failures cause a message to remain in the queue for longer than delay. Each delay parameter consists of a positive decimal integer and a unit s, m, h, or d. At most four delay parameters can be specified. The default is "bounce warn-interval 4h", sending a single warning after four hours. ca caname cert cafile Associate the Certificate Authority (CA) certificate file cafile with ca entry caname. The ca entry can be referenced in listen on and action ... relay rules. filter chain-name chain {filter-name [, ...]} Register a chain of filters chain-name, consisting of the fil- ters listed in filter-name. Filters in a filter chain are exe- cuted in order of declaration for each phase that they are reg- istered for. A filter chain may be used in place of a filter for any directive except filter chains themselves. filter filter-name phase phase-name match conditions decision Register a filter filter-name. A decision about what to do with the mail is taken at phase phase-name when matching conditions. Phases, matching conditions, and decisions are de- scribed in "MAIL FILTERING", below. filter filter-name proc proc-name Register "proc" filter filter-name backed by the proc-name process. filter filter-name proc-exec command Register and execute "proc" filter filter-name from command, conformant with the smtpd-filters(7) API. If command starts with a slash it is executed with an absolute path, otherwise it will be run from "/usr/local/libexec/opensmtpd". include "pathname" Replace this directive with the content of the additional con- figuration file at the absolute pathname. listen on interface [family] [options] Listen on the interface for incoming connections, using the same syntax as ifconfig(8). The interface parameter may also be an interface group, an IP address, or a domain name. Lis- tening can optionally be restricted to a specific address family, which can be either inet4 or inet6. The options are as follows: auth [<authtable>] Support SMTPAUTH: clients may only start SMTP transac- tions after successful authentication. Users are au- thenticated against either their own normal login cre- dentials or a credentials table authtable, the format of which is described in table(5). auth-optional [<authtable>] Support SMTPAUTH optionally: clients need not authenti- cate, but may do so. This allows a listen on directive to both accept incoming mail from untrusted senders and permit outgoing mail from authenticated users (using match auth). It can be used in situations where it is not possible to listen on a separate port (usually the submission port, 587) for users to authenticate. ca caname For secure connections, use the CA certificate associ- ated with caname (declared in a ca directive) as the CA certificate when verifying client certificates. filter name Apply filter name on connections handled by this lis- tener. hostname hostname Use hostname in the greeting banner instead of the de- fault server name. hostnames <names> Override the server name for specific addresses. The names table contains a mapping of IP addresses to host- names. If the address on which the connection arrives appears in the mapping, the associated hostname is used. mask-src Omit the from part when prepending "Received" headers. no-dsn Disable the DSN (Delivery Status Notification) exten- sion. pki pkiname For secure connections, use the certificate associated with pkiname (declared in a pki directive) to prove a mail server's identity. This option can be used multi- ple times to provide alternate certificates for SNI. port [port] Listen on the given port instead of the default port 25. proxy-v2 Support the PROXYv2 protocol, appropriately rewriting the source address received from proxy. received-auth In "Received" headers, report whether the session was authenticated and by which local user. senders <users> [masquerade] Look up the authenticated user in the users mapping ta- ble to find the email addresses that user is allowed to submit mail as. In addition, if the masquerade option is provided, the From header is rewritten to match the sender provided in the SMTP session. smtps Support SMTPS, by default on port 465. Mutually exclu- sive with tls. tag tag Clients connecting to the listener are tagged with the given tag. tls Support STARTTLS, by default on port 25. Mutually ex- clusive with smtps. tls-require [verify] Like tls, but force clients to establish a secure con- nection before being allowed to start an SMTP transac- tion. With the verify option, clients must also pro- vide a valid certificate to establish an SMTP session. protocols protostr Define the protocol versions to be used for TLS ses- sions. Refer to the tls_config_parse_protocols(3) man- page for the format of protostr. ciphers cipherstr Define the list of ciphers that may be used for TLS sessions. Refer to the tls_config_set_ciphers(3) man- page for the format of cipherstr. listen on socket [options] Listen for incoming SMTP connections on the Unix domain socket /var/run/smtpd.sock. This is done by default, even if the di- rective is absent. The options are as follows: filter name Apply filter name on connections handled by this lis- tener. mask-src Omit the from part when prepending "Received" headers. no-dsn Disable the DSN (Delivery Status Notification) exten- sion. tag tag Clients connecting to the listener are tagged with the given tag. match options action name If at least one mail envelope matches the options of one match action directive, receive the incoming message, put a copy into each matching envelope, and atomically save the envelopes to the mail spool for later processing by the respective dis- patcher name. The following matching options are supported and can all be negated: [!] for any Specify that session may address any destination. [!] for local Specify that session may address any local domain. This is the default, and may be omitted. [!] for domain domain | <domain> Specify that session may address the string or list ta- ble domain. [!] for domain regex domain | <domain> Specify that session may address the regex or regex ta- ble domain. [!] for rcpt-to recipient | <recipient> Specify that session may address the string or list ta- ble recipient. [!] for rcpt-to regex recipient | <recipient> Specify that session may address the regex or regex ta- ble recipient. [!] from any Specify that session may originate from any source. [!] from auth Specify that session may originate from any authenti- cated user, no matter the source IP address. [!] from auth user | <user> Specify that session may originate from authenticated user or user list user, no matter the source IP ad- dress. [!] from auth regex user | <user> Specify that session may originate from authenticated regex or regex list user, no matter the source IP ad- dress. [!] from local Specify that session may only originate from a local IP address, or from the local enqueuer. This is the de- fault, and may be omitted. [!] from mail-from sender | <sender> Specify that session may originate from sender or sender list sender, no matter the source IP address. [!] from mail-from regex sender | <sender> Specify that session may originate from regex or regex list sender, no matter the source IP address. [!] from rdns Specify that session may only originate from an IP ad- dress that resolves to a reverse DNS. [!] from rdns hostname | <hostname> Specify that session may only originate from an IP ad- dress that resolves to a reverse DNS matching string or list string hostname. [!] from rdns regex hostname | <hostname> Specify that session may only originate from an IP ad- dress that resolves to a reverse DNS matching regex or list regex hostname. [!] from socket Specify that session may only originate from the local enqueuer. [!] from src address | <address> Specify that session may only originate from string or list table address which can be a specific address or a subnet expressed in CIDR-notation. [!] from src regex address | <address> Specify that session may only originate from regex or regex table address which can be a specific address or a subnet expressed in CIDR-notation. In addition, the following transaction options may be matched: [!] auth Matches transactions which have been authenticated. [!] auth username | <username> Matches transactions which have been authenticated for user or user list username. [!] auth regex username | <username> Matches transactions which have been authenticated for regex or regex list username. [!] helo helo-name | <helo-name> Specify that session's HELO / EHLO should match the string or list table helo-name. [!] helo regex helo-name | <helo-name> Specify that session's HELO / EHLO should match the regex or regex table helo-name. [!] mail-from sender | <sender> Specify that transaction's MAIL FROM should match the string or list table sender. [!] mail-from regex sender | <sender> Specify that transaction's MAIL FROM should match the regex or regex table sender. [!] rcpt-to recipient | <recipient> Specify that transaction's RCPT TO should match the string or list table recipient. [!] rcpt-to regex recipient | <recipient> Specify that transaction's RCPT TO should match the regex or regex table recipient. [!] tag tag Matches transactions tagged with the given tag. [!] tag regex tag Matches transactions tagged with the given tag regex. [!] tls Specify that transaction should take place in a TLS channel. match options reject Reject the incoming message during the SMTP dialogue. The same options are supported as for the match action directive. mda wrapper name command Associate command with the mail delivery agent wrapper named name. When a local delivery specifies a wrapper, the command associated with the wrapper will be executed instead. The com- mand may contain format specifiers (see "FORMAT SPECIFIERS"). mta max-deferred number When delivery to a given host is suspended due to temporary failures, cache at most number envelopes for that host such that they can be delivered as soon as another delivery succeeds to that host. The default is 100. pki pkiname cert certfile Associate certificate file certfile with pki entry pkiname. The pki entry defines a keypair configuration that can be ref- erenced in listener rules and relay actions. A certificate chain may be created by appending one or many certificates, including a Certificate Authority certificate, to certfile. The creation of certificates is documented in starttls(8). pki pkiname key keyfile Associate the key located in keyfile with pki entry pkiname. pki pkiname dhe params Specify the DHE parameters to use for DHE cipher suites with pki entry pkiname. Valid parameter values are none, legacy, and auto. For legacy, a fixed key length of 1024 bits is used, whereas for auto, the key length is determined automatically. The default is none, which disables DHE cipher suites. proc proc-name command Register an external process named proc-name from command, con- formant with the smtpd-filters(7) API. Such processes may be used to share the same instance between multiple filters. If command starts with a slash it is executed with an absolute path, otherwise it will be run from "/usr/local/libexec/opensmtpd". queue compression Store queue files in a compressed format. This may be useful to save disk space. queue encryption [key] Encrypt queue files with EVP_aes_256_gcm(3). If no key is specified, it is read with getpass(3). If the string stdin or a single dash (`-') is given instead of a key, the key is read from the standard input. queue ttl delay Set the default expiration time for temporarily undeliverable messages, given as a positive decimal integer followed by a unit s, m, h, or d. The default is four days (4d). smtp ciphers control Set the control string for SSL_CTX_set_cipher_list(3). The de- fault is "HIGH:!aNULL:!MD5". smtp limit max-mails count Limit the number of messages to count for each session. The default is 100. smtp limit max-rcpt count Limit the number of recipients to count for each transaction. The default is 1000. smtp max-message-size size Reject messages larger than size, given as a positive number of bytes or as a string to be parsed with scan_scaled(3). The de- fault is "35M". smtp sub-addr-delim character When resolving the local part of a local email address, ignore the ASCII character and all characters following it. The de- fault is `+'. srs key secret Set the secret key to use for SRS, the Sender Rewriting Scheme. srs key backup secret Set a backup secret key to use as a fallback for SRS. This can be used to implement SRS key rotation. srs ttl delay Set the time-to-live delay for SRS envelopes. After this de- lay, a bounce reply to the SRS address will be discarded to limit risks of forged addresses. The default is four days (4d). table name [type:]pathname Tables provide additional configuration information for smtpd(8) in the form of lists or key-value mappings. The for- mat of the entries depends on what the table is used for. Re- fer to table(5) for the exhaustive documentation. Each table is identified by an arbitrary, unique name. If the type is db, information is stored in a file created with makemap(8); if it is file or omitted, information is stored in a plain text file using the format described in table(5). The pathname to the file must be absolute. table name {value [, ...]} Instead of using a separate file, declare a list table contain- ing the given static values. The table must contain at least one value and may declare multiple values as a comma-separated (whitespace optional) list. table name {key=value [, ...]} Instead of using a separate file, declare a mapping table con- taining the given static key-value pairs. The table must con- tain at least one key-value pair and may declare multiple pairs as a comma-separated (whitespace optional) list. MAIL FILTERING In a regular workflow, smtpd(8) may accept or reject a message based only on the content of envelopes. Its decisions are about the handling of the message, not about the handling of an active session. Filtering extends the decision making process by allowing smtpd(8) to stop at each phase of an SMTP session, check that conditions are met, then decide if a session is allowed to move forward. With filtering, a session may be interrupted at any phase before an en- velope is complete. A message may also be rejected after being submit- ted, regardless of whether the envelope was accepted or not. The following phases are currently supported: connect upon connection, before a banner is displayed helo after HELO command is submitted ehlo after EHLO command is submitted mail-from after MAIL FROM command is submitted rcpt-to after RCPT TO command is submitted data after DATA command is submitted commit after message is fully is submitted At each phase, various conditions may be matched. The fcrdns, rdns, and src data are available in all phases, but other data must have been already submitted before they are available. fcrdns forward-confirmed reverse DNS is valid rdns session has a reverse DNS rdns <table> session has a reverse DNS in table src <table> source address is in table helo <table> helo name is in table auth session is authenticated auth <table> session username is in table mail-from <table> sender address is in table rcpt-to <table> recipient address is in table These conditions may all be negated by prefixing them with an exclama- tion mark: !fcrdns forward-confirmed reverse DNS is invalid Any conditions using a table may indicate that the table contains regu- lar expressions by prefixing the table name with the keyword regex. helo regex <table> helo name matches a regex in table Finally, a number of decisions may be taken: bypass the session or transaction bypasses filters disconnect message the session is disconnected with message junk the session or transaction is junked, i.e., an `X-Spam: yes' header is added to any messages reject message the command is rejected with message rewrite value the command parameter is rewritten with value Decisions that involve a message require that the message be RFC valid, meaning that they should either start with a 4xx or 5xx status code. Decisions can be taken at any phase, though junking can only happen be- fore a message is committed. FORMAT SPECIFIERS Some configuration directives support expansion of their parameters at runtime. Such directives (for example action maildir, action mda) may use format specifiers which are expanded before delivery or relaying. The following formats are currently supported: %{sender} sender email address, may be empty string %{sender.user} user part of the sender email address, may be empty %{sender.domain} domain part of the sender email address, may be empty %{rcpt} recipient email address %{rcpt.user} user part of the recipient email address %{rcpt.domain} domain part of the recipient email address %{dest} recipient email address after expansion %{dest.user} user part after expansion %{dest.domain} domain part after expansion %{user.username} local user %{user.directory} home directory of the local user %{mbox.from} name used in mbox From separator lines %{mda} mda command, only available for mda wrappers Expansion formats also support partial expansion using the optional bracket notations with substring offset. For example, with recipient domain "example.org": %{rcpt.domain[0]} expands to "e" %{rcpt.domain[1]} expands to "x" %{rcpt.domain[8:]} expands to "org" %{rcpt.domain[-3:]} expands to "org" %{rcpt.domain[0:6]} expands to "example" %{rcpt.domain[0:-4]} expands to "example" In addition, modifiers may be applied to the token. For example, with recipient "User+Tag@Example.org": %{rcpt:lowercase} expands to "user+tag@example.org" %{rcpt:uppercase} expands to "USER+TAG@EXAMPLE.ORG" %{rcpt:strip} expands to "User@Example.org" %{rcpt:lowercase|strip} expands to "user@example.org" For security concerns, expanded values are sanitized and potentially dangerous characters are replaced with `:'. In situations where they are desirable, the "raw" modifier may be applied. For example, with recipient "user+t?g@example.org": %{rcpt} expands to "user+t:g@example.org" %{rcpt:raw} expands to "user+t?g@example.org" MDA COMMANDS When an action delivery method is mda, smtpd(8) runs the associated command for the delivery with the mail content provided via standard input. The command is expected to read all the mail content. The exit code of the command reports the outcome of the delivery: sta- tus 0 (EX_OK) is a successful delivery; status 71 (EX_OSERR) and 75 (EX_TEMPFAIL) are temporary failures; and all other exit status are considered permanent failures. The following environment variables are set: DOMAIN The recipient domain. EXTENSION The sub address of the recipient (may be unset). HOME The delivery user's login directory. LOCAL The local part of the recipient user address. LOGNAME The login name of the user. ORIGINAL_RECIPIENT The address of the original recipient. PATH Set to _PATH_DEFPATH. Traditionally /usr/bin:/bin, but expanded to include /usr/sbin, /sbin, /usr/X11R6/bin, /usr/local/bin, and /usr/local/sbin in OpenBSD. RECIPIENT The address of the final recipient. SENDER The address of the sender (might be empty). SHELL Set to /bin/sh. USER Synonym of LOGNAME for backwards compatibility. FILES /usr/local/etc/mail/smtpd.conf Default smtpd(8) configuration file. /usr/local/etc/mail/mailname If this file exists, the first line is used as the server name. Other- wise, the server name is derived from the local hostname returned by gethostname(3), either directly if it is a fully qualified domain name, or by retrieving the associated canonical name through getaddrinfo(3). /var/run/smtpd.sock Unix domain socket for incoming SMTP connections. /var/spool/smtpd/ Spool directories for mail during processing. EXAMPLES The default smtpd.conf file which ships with OpenBSD listens on the loopback network interface (lo0) and allows for mail from users and daemons on the local machine, as well as permitting email to remote servers. Some more complex configurations are given below. This first example is similar to the default configuration, but all outgoing mail is forwarded to a remote SMTP server. A secrets file is needed to specify a username and password: # touch /usr/local/etc/mail/secrets # chmod 640 /usr/local/etc/mail/secrets # chown root:_smtpd /usr/local/etc/mail/secrets # echo "bob username:password" > /usr/local/etc/mail/secrets smtpd.conf would look like this: table aliases file:/usr/local/etc/mail/aliases table secrets file:/usr/local/etc/mail/secrets listen on lo0 action "local_mail" mbox alias <aliases> action "outbound" relay host smtp+tls://bob@smtp.example.com \ auth <secrets> match from local for local action "local_mail" match from local for any action "outbound" In this second example, the aim is to permit mail delivery and relaying only for users that can authenticate (using their normal login creden- tials). An RSA certificate must be provided to prove the server's identity. The mail server listens on all interfaces the default routes point to. Mail with a local destination is sent to an external MDA. First, the RSA certificate is created: # openssl genrsa -out /etc/ssl/private/mail.example.com.key 4096 # openssl req -new -x509 -key /etc/ssl/private/mail.example.com.key \ -out /etc/ssl/mail.example.com.crt -days 365 # chmod 600 /etc/ssl/mail.example.com.crt # chmod 600 /etc/ssl/private/mail.example.com.key In the example above, a certificate valid for one year was created. The configuration file would look like this: pki mail.example.com cert "/etc/ssl/mail.example.com.crt" pki mail.example.com key "/etc/ssl/private/mail.example.com.key" table aliases file:/usr/local/etc/mail/aliases listen on lo0 listen on egress tls pki mail.example.com auth action mda_with_aliases mda "/path/to/mda -f -" alias <aliases> action mda_without_aliases mda "/path/to/mda -f -" action "outbound" relay match for local action mda_with_aliases match from any for domain example.com action mda_without_aliases match for any action "outbound" match auth from any for any action "outbound" For sites that wish to sign messages using DKIM, the following example uses opensmtpd-filter-dkimsign for DKIM signing: table aliases file:/usr/local/etc/mail/aliases filter "dkimsign" proc-exec "filter-dkimsign -d <domain> -s <selector> \ -k /usr/local/etc/mail/dkim/private.key" user _dkimsign group _dkimsign listen on socket filter "dkimsign" listen on lo0 filter "dkimsign" action "local_mail" mbox alias <aliases> action "outbound" relay match for local action "local_mail" match for any action "outbound" Alternatively, the opensmtpd-filter-rspamd package may be used to pro- vide integration with rspamd, a third-party daemon which provides mul- tiple antispam features as well as DKIM signing. As well as configur- ing rspamd itself, it requires use of the proc-exec keyword: filter "rspamd" proc-exec "filter-rspamd" Sites that accept non-local messages may be able to cut down on the volume of spam received by rejecting forged messages that claim to be from the local domain. The following example uses a list table other-relays to specify the IP addresses of relays that may legiti- mately originate mail with the owner's domain as the sender. table aliases file:/usr/local/etc/mail/aliases table other-relays file:/usr/local/etc/mail/other-relays listen on lo0 listen on egress action "local_mail" mbox alias <aliases> action "outbound" relay match for local action "local_mail" match for any action "outbound" match !from src <other-relays> mail-from "@example.com" for any \ reject match from any for domain example.com action "local_mail" SEE ALSO mailer.conf(5), table(5), smtpd-filters(7), makemap(8), smtpd(8) HISTORY smtpd(8) first appeared in OpenBSD 4.6. FreeBSD 14.3 July 26, 2024 SMTPD.CONF(5)
NAME | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | HISTORY
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