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opendkim.conf

NAME

opendkim.conf - Configuration file for opendkim

LOCATION

/etc/mail/opendkim.conf

DESCRIPTION

opendkim(8) implements the DKIM specification for signing and verifying e-mail messages on a per-domain basis. This file is its configuration file.

Blank lines are ignored. Lines containing a hash ("#") character are truncated at the hash character to allow for comments in the file.

Other content should be the name of a parameter, followed by white space, followed by the value of that parameter, each on a separate line.

For parameters that are Boolean in nature, only the first byte of the value is processed. For positive values, the following are accepted: "T", "t", "Y", "y", "1". For negative values, the following are accepted: "F", "f", "N", "n", "0".

Many, but not all, of these parameters are also available as command line options to opendkim(8). However, new parameters are generally not added as command line options so the complete set of options is available here, and thus use of the configuration file is encouraged. In some future release, the set of available command line options is likely to get trimmed.

See the opendkim(8) man page for details about how and when the configuration file contents are reloaded.

Some of these parameters are listed as having a type of "dataset". See the opendkim(8) man page for a description of such parameters.

PARAMETERS

ADSPDiscard (Boolean)

If "true", requests rejection of messages that are determined to be suspicious according to the author domain's published signing practises (ADSP) record if that record also recommends discard of such messages.

ADSPNoSuchDomain (Boolean)

If "true", requests rejection of messages that are determined to be from nonexistent domains according to the author domain signing practises (ADSP) test.

AllowSHA1Only (Boolean)

Permit verify mode when only SHA1 support is available. RFC4871 requires that verifiers implement both SHA1 and SHA256 support. Setting this feature changes the absence of SHA256 support from an error to a warning.

AlwaysAddARHeader (Boolean)

Add an "Authentication-Results:" header field even to unsigned messages from domains with no "signs all" policy. The reported DKIM result will be "none" in such cases. Normally unsigned mail from non-strict domains does not cause the results header to be added.

AlwaysSignHeaders (dataset)

Specifies a set of header fields that should be included in all signature header lists (the "h=" tag) even if they were not present at the time the signature was generated. The set is empty by default. The purpose of listing an absent header is to prevent its addition between the signer and the verifier, since the verifier would include that header if it were added when performing verification, which would mean the signed message and the verified message were different and the verification would fail.

AuthservID (string)

Sets the "authserv-id" to use when generating the Authentication-Results: header after verifying a message. The default is to use the local machine's hostname.

AuthservIDWithJobID (Boolean)

If "true", requests that the authserv-id portion of the added Authentication-Results: headers contain the job ID of the message being evaluated.

AutoRestart (Boolean)

Automatically re-start on failures. Use with caution; if the filter fails instantly after it starts, this can cause a tight fork(2) loop.

AutoRestartCount (integer)

Sets the maximum automatic restart count. After this number of automatic restarts, the filter will give up and terminate. A value of 0 implies no limit; this is the default.

AutoRestartRate (string)

Sets the maximum automatic restart rate. If the filter begins restarting faster than the rate defined here, it will give up and terminate. This is a string of the form n/t[u] where n is an integer limiting the count of restarts in the given interval and t[u] defines the time interval through which the rate is calculated; t is an integer and u defines the units thus represented ("s" or "S" for seconds, the default; "m" or "M" for minutes; "h" or "H" for hours; "d" or "D" for days). For example, a value of "10/1h" limits the restarts to 10 in one hour. There is no default, meaning restart rate is not limited.

Background (Boolean)

Normally opendkim forks and exits immediately, leaving the service running in the background. This flag suppresses that behaviour so that it runs in the foreground.

BaseDirectory (string)

If set, instructs the filter to change to the specified directory using chdir(2) before doing anything else. This means any files referenced elsewhere in the configuration file can be specified relative to this directory. It's also useful for arranging that any crash dumps will be saved to a specific location.

BodyLengths (Boolean)

Requests that opendkim include the "l=" body length tag when generating signatures. This indicates to the verifier that only a certain amount of the original message was signed, allowing tolerance of things like mailing list managers that append list-specific text to the end of mailings it processes. However, this also enables an abuse attack. See the DKIM specification for more information.

BodyLengthDBFile (dataset)

Requests that opendkim include a "l=" body length tag when the set contains the recipient addresses. (feature is experimental)

BogusKey (string)

Instructs the filter to treat a passing signature associated with a bogus (forged) key in a special way. Possible values are neutral (return a "neutral" result), none (take no special action) and fail (return a "fail" result; this is the default).

BogusPolicy (string)

Instructs the filter to treat an ADSP policy found in an bogus (forged) DNS record in a special way. Possible values are apply (apply the policy) and ignore (ignore the policy; this is the default).

Canonicalization (string)

Selects the canonicalization method(s) to be used when signing messages. When verifying, the message's DKIM-Signature: header specifies the canonicalization method. The recognized values are relaxed and simple as defined by the DKIM specification. The default is simple. The value may include two different canonicalizations separated by a slash ("/") character, in which case the first will be applied to the headers and the second to the body.

ClockDrift (integer)

Sets the tolerance in seconds to be applied when determining whether a signature was either expired or generated in the future. The default is 300.

Diagnostics (Boolean)

Requests the inclusion of "z=" tags in signatures, which encode the original header set for use by verifiers when diagnosing verification failures. Not recommended for normal operation.

DiagnosticDirectory (string)

Store diagnostic files in this directory. (feature is experimental)

DNSTimeout (integer)

Sets the DNS timeout in seconds. A value of 0 causes an infinite wait. The default is 5. Ignored if not using the asynchronous resolver package. See also the NOTES section below.

Domain (dataset)

A set of domains whose mail should be signed by this filter. Mail from other domains will be verified rather than being signed.

This parameter is not required if a SigningTable is in use; in that case, the list of signed domains is implied by the lines in that file.

DontSignMailTo (dataset)

A set of e-mail address, mail to which should never be signed by the filter. Note that this is an "any" feature; if any one of the recipients of the message matches a member of this list, the message will not be signed.

EnableCoredumps (boolean)

On systems that have such support, make an explicit request to the kernel to dump cores when the filter crashes for some reason. Some modern UNIX systems suppress core dumps during crashes for security reasons if the user ID has changed during the lifetime of the process. Currently only supported on Linux.

ExemptDomains (dataset)

Specifies a set of domains, mail from which should be ignored entirely by the filter. This is similar to the PeerList setting except that it bases its decision on the sender of the message as identified from the header fields or other message data, not the identity of the SMTP client sending the message.

ExternalIgnoreList (dataset)

Identifies a set of "external" hosts that may send mail through the server as one of the signing domains without credentials as such. Basically suppresses the "external host (hostname) tried to send mail as (domain)" log messages. Entries in the data set should be of the same form as those of the PeerList option below. The set is empty by default.

FinalPolicyScript (string)

Gives the name of a Lua script that should be run after the entire message has been received. This can be used to enact local policy decisions such as message rejection, quarantine, rerouting, etc. based on signatures found on the message, the results of attempts to verify them, and other properties of the message or signatures. See opendkim-lua(3) for details.

FixCRLF (Boolean)

Requests that the DKIM library convert bare CRs and LFs to CRLFs during body canonicalization, anticipating that an MTA somewhere before delivery will do that conversion anyway. The default is to leave them as-is.

IdentityHeader (string)

This specifies the header where an identity is stored. (Experimental feature not enabled for this installation.)

IdentityHeaderRemove (Boolean)

Remove the IdentityHeader after signing. (Experimental feature not enabled for this installation.)

Include (string)

Names a file to be opened and read as an additional configuration file. Nesting is allowed to a maximum of five levels.

InsecureKey (string)

Instructs the filter to treat a passing signature associated with an insecure key in a special way. Possible values are neutral (return a "neutral" result), none (take no special action; this is the default) and fail (return a "fail" result).

InsecurePolicy (string)

Instructs the filter to treat an ADSP policy found in an insecure DNS record in a special way. Possible values are apply (apply the policy; this is the default) and ignore (ignore the policy).

InternalHosts (dataset)

Identifies a set internal hosts whose mail should be signed rather than verified. Entries in this data set follow the same form as those of the PeerList option below. If not specified, the default of "127.0.0.1" is applied. Naturally, providing a value here overrides the default, so if mail from 127.0.0.1 should be signed, the list provided here should include that address explicitly.

KeepTemporaryFiles (boolean)

Instructs the filter to create temporary files containing the header and body canonicalizations of messages that are signed or verified. The location of these files can be set using the TemporaryDirectory parameter. Intended only for debugging verification problems.

KeyFile (string)

Gives the location of a PEM-formatted private key to be used for signing all messages. Ignored if a KeyTable is defined.

KeyTable (dataset)

Gives the location of a file mapping key names to signing keys. If present, overrides any KeyFile setting in the configuration file. The data set named here maps each key name to three values: (a) the name of the domain to use in the signature's "d=" value; (b) the name of the selector to use in the signature's "s=" value; and (c) either a private key or a path to a file containing a private key. If the third value starts with a slash ("/") character, or "./" or "../", then it is presumed to refer to a file from which the private key should be read, otherwise it is itself a PEM-encoded private key or a base64-encoded DER private key. The SigningTable (see below) is used to select records from this table to be used to add signatures based on the message sender.

LDAPAuthMechanism (string)

Names the authentication mechanism to use when connecting to an LDAP server. The default is the empty string, meaning "simple" authentication should be done.

LDAPAuthName (string)

Specifies the authenticating name to use when using SASL to authenticate to an LDAP server. Requires SASL support be installed on the local system. There is no default.

LDAPAuthRealm (string)

Specifies the authentication realm to use when using SASL to authenticate to an LDAP server. Requires SASL support be installed on the local system. There is no default.

LDAPAuthUser (string)

Specifies the authenticating user to use when using SASL to authenticate to an LDAP server. Requires SASL support be installed on the local system. There is no default.

LDAPBindPassword (string)

Specifies the password to use when conducting an LDAP "bind" operation. There is no default.

LDAPBindUser (string)

Specifies the user ID to use when conducting an LDAP "bind" operation. There is no default.

LDAPUseTLS (Boolean)

Indicates whether or not a TLS connection should be established when contacting an LDAP server. The default is "False".

LocalADSP (dataset)

Allows specification of local ADSP overrides for domains. This is expected to be a data set with keys and matching values; the keys are each either a fully-qualified domain name (e.g. "foo.example.com") or a subdomain name preceded by a period (e.g. ".example.com"), and the values are either unknown, all, or discardable, as per the ADSP specification (RFC5617). This allows local overrides of policies to enforce for domains that either don't publish ADSP or publish weaker policies than the verifier would like to enforce.

LogWhy (boolean)

If logging is enabled (see Syslog below), issues very detailed logging about the logic behind the filter's decision to either sign a message or verify it. The logic behind the decision is non-trivial and can be confusing to administrators not familiar with its operation. A description of how the decision is made can be found in the OPERATIONS section of the opendkim(8) man page. This causes a large increase in the amount of log data generated for each message, so it should be limited to debugging use and not enabled for general operation.

MacroList (dataset)

Defines a set of MTA-provided macros that should be checked to see if the sender has been determined to be a local user and therefore whether or not the message should be signed. If a value is specified matching a macro name in the data set, the value of the macro must match a value specified (matching is case-sensitive), otherwise the macro must be defined but may contain any value. The set is empty by default, meaning macros are not considered when making the sign-verify decision. The general format of the value is value1[|value2[|...]]; if one or more value is defined then the macro must be set to one of the listed values, otherwise the macro must be set but can contain any value.

In order for the macro and its value to be available to the filter for checking, the MTA must send it during the protocol exchange. This is either accomplished via manual configuration of the MTA to send the desired macros or, for MTA/filter combinations that support the feature, the filter can request those macros that are of interest. The latter is a feature negotiated at the time the filter receives a connection from the MTA and its availability depends upon the version of milter used to compile the filter and the version of the MTA making the connection.

MaximumHeaders (integer)

Defines the maximum number of bytes the header block of a message may consume before the filter will reject the message. This mitigates a denial-of-service attack in which a client connects to the MTA and begins feeding an unbounded number of header fields of arbitrary size; since the filter keeps a cache of these, the attacker could cause the filter to allocate an unspecified amount of memory. The default is 65536; a value of 0 removes the limit.

MaximumSignedBytes (integer)

Specifies the maximum number of bytes of message body to be signed. Messages shorter than this limit will be signed in their entirety. Setting this value forces BodyLengths to be "True".

MilterDebug (integer)

Sets the debug level to be requested from the milter library. The default is 0.

Minimum (string)

Instructs the verification code to fail messages for which a partial signature was received. There are three possible formats: min indicating at least min bytes of the message must be signed (or if the message is smaller than min then all of it must be signed); min% requiring that at least min percent of the received message must be signed; and min+ meaning there may be no more than min bytes of unsigned data appended to the message for it to be considered valid.

Mode (string)

Selects operating modes. The string is a concatenation of characters that indicate which mode(s) of operation are desired. Valid modes are s (signer) and v (verifier). The default is sv except in test mode (see the opendkim(8) man page) in which case the default is v. When signing mode is enabled, one of the following combinations must also be set: (a) Domain, KeyFile, Selector, no KeyTable, no SigningTable; (b) KeyTable, SigningTable, no Domain, no KeyFile, no Selector; (c) KeyTable, SetupPolicyScript, no Domain, no KeyFile, no Selector.

MTA (dataset)

A set of MTA names (a la the sendmail(8) DaemonPortOptions Name parameter) whose mail should be signed by this filter. There is no default, meaning MTA name is not considered when making the sign-verify decision.

MultipleSignatures (Boolean)

Allow addition of multiple signatures when key lists are in use. See SigningTable for more information.

MustBeSigned (dataset)

Specifies a set of headers that, if present, must be covered by the DKIM signature when verifying a message. If a header in this set is present in the message and is not signed, the filter will treat even an otherwise valid signature as invalid. The default is an empty list.

OmitHeaders (dataset)

Specifies a set of header fields that should be omitted when generating signatures. If an entry in the list names any header that is mandated by the DKIM specification, the entry is ignored. A set of headers is listed in the DKIM specification as "SHOULD NOT" be signed; the default list for this parameter contains those headers (Return-Path, Received, Comments, Keywords, Bcc, Resent-Bcc and DKIM-Signature). To omit no headers, simply use the string "-" (or any string that will match no headers). Note that specifying a list with this parameter replaces the default entirely.

On-BadSignature (string)

Selects the action to be taken when a signature fails to validate. Possible values (with abbreviated forms in parentheses): accept (a) accept the message; discard (d) discard the message; tempfail (t) temp-fail the message; reject (r) reject the message. The default is accept.

On-Default (string)

Selects the action to be taken when any verification or internal error of any kind is encountered. This is processed before the other "On-" values so it can be used as a blanket setting followed by specific overrides.

On-DNSError (string)

Selects the action to be taken when a transient DNS error is encountered. Possible values are the same as those for On-BadSignature. The default is tempfail.

On-InternalError (string)

Selects the action to be taken when an internal error of some kind is encountered. Possible values are the same as those for On-BadSignature. The default is tempfail.

On-KeyNotFound (string)

Selects the action to be taken when the key referenced by a signature is not present in the DNS. Possible values are the same as those for On-BadSignature. The default is accept.

On-NoSignature (string)

Selects the action to be taken when a message arrives unsigned. Possible values are the same as those for On-BadSignature. The default is accept.

On-PolicyError (string)

Selects the action to be taken when a an attempt to retrieve and evaluate the author domain's signing policy (ADSP) is unsuccessful. Possible values are the same as those for On-BadSignature. The default is accept.

On-Security (string)

Selects the action to be taken when a message arrives containing properties that may be a security concern. Possible values are the same as those for On-BadSignature. The default is tempfail.

PeerList (dataset)

Identifies a set of "peers" that identifies clients whose connections should be accepted without processing by this filter. The set should contain on each line a hostname, domain name (e.g. ".example.com"), IP address, an IPv6 address (including an IPv4 mapped address), or a CIDR-style IP specification (e.g. "192.168.1.0/24"). An entry beginning with a bang ("!") character means "not", allowing exclusions of specific hosts that are otherwise members of larger sets. More precise entries are preferred over less precise ones, i.e. "192.168.1.1" will match before "!192.168.1.0/24". The text form of IPv6 addresses will be forced to lowercase when queried (which is a proposed standard), so the contents of this data set should also use lowercase.

PidFile (string)

Specifies the path to a file that should be created at process start containing the process ID.

POPDBFile (dataset)

Requests that the filter consult a set for IP addresses that should be allowed for signing. This feature was designed for POP-before-SMTP datastores. (Not enabled for this installation.)

Quarantine (Boolean)

Requests that messages that fail verification be quarantined by the MTA. (Requires a sufficiently recent version of the milter library.)

QueryCache (Boolean)

Instructs the DKIM library to maintain its own local cache of keys and policies retrieved from DNS, rather than relying on the nameserver for caching service. Useful if the nameserver being used by the filter is not local. (Not enabled for this installation.)

ReplaceRules (string)

Specifies a file containing a list of POSIX regular expressions that are applied the the message headers. (feature is experimental)

ReportIntervalDB (dataset)

Specifies a set of domains that correspond to how often, in seconds, to report DKIM signature failues. See SendReports for more details. (feature is experimental)

RemoveARAll (Boolean)

Removes all Authentication-Results: header fields that also satisfy the requirements of RemoveARFrom below. By default, only those containing a DKIM result are removed.

RemoveARFrom (dataset)

Defines a set of hostnames whose Authentication-Results: header fields should be removed before the message is passed for delivery. By default only those headers matching the local host's canonical name will be removed. Matching is only done on full hostnames (e.g. "host.example.com") or on domain names (e.g. ".example.com").

RemoveOldSignatures (Boolean)

Removes all existing signatures when operating in signing mode.

ReportAddress (string)

Specifies the string to use in the From: header field for outgoing reports (see SendReports and SendADSPReports below). If not specified, the executing user and local hostname will be used to construct the address.

ReputationFail (integer)

If the reputation returned by the DNS reputation service exceeds this value then the Authenticated Header result "x-dkim-rep" is set to "fail". Defaults to 0. (Experimental feature not enabled for this installation.)

ReputationPass (integer)

If the reputation returned by the DNS reputation service is less than this value then the Authenticated Header result "x-dkim-rep" is set to "pass". Defaults to 0. Values in between ReputationFail and ReputationPass result in "x-dkim-rep" being set to "neutral". (Experimental feature not enabled for this installation.)

ReputationReject (integer)

If the reputation returned by the DNS reputation service exceeds this value then the message is rejected. The default value here is 1001. (Experimental feature not enabled for this installation.)

ReputationRoot (string)

This is the root directory of the DNS reputation service. Its interface is defined at http://www.dkim-reputation.org. The default value here is "al.dkim-reputation.org". (Experimental feature not enabled for this installation.)

RequiredHeaders (boolean)

Checks all messages for compliance with RFC5322 header field count requirements. Non-compliant messages are rejected.

ResignAll (boolean)

Where ResignMailTo triggers a re-signing action, this flag indicates whether or not all mail should be signed (if set) versus only verified mail being signed (if not set). The default is "false". (Experimental feature not enabled for this installation.)

ResignMailTo (dataset)

Checks each message recipient against the specified dataset for a matching record. The full address is checked in each case, then the hostname, then each domain preceded by ".". If there is a match, the value returned is presumed to be the name of a key in the KeyTable (if defined) to be used to re-sign the message in addition to verifying it. If there is a match without a KeyTable, the default key is applied. (Experimental feature not enabled for this installation.)

ScreenPolicyScript (string)

Gives the name of a Lua script that should be run after all of the header fields have been processed for a message; in particular, this is useful after all DKIM signatures have been detected and initial evaluation has been done. The script has access to all of the headers and connection information and can that certain signatures be ignored based on that information. See opendkim-lua(3) for details.

Selector (string)

Defines the name of the selector to be used when signing messages. See the DKIM specification for details. Used only when signing with a single key; see the SigningTable parameter below for more information.

SelectorHeader (string)

Names a header field whose contents name the key to use when signing. The referenced key must appear in the KeyTable. (feature is experimental)

SelectorHeaderRemove (Boolean)

Remove the SelectorHeader before signing. (feature is experimental)

SendADSPReports (Boolean)

If true, when a policy evaluation fails and the signing site advertises a reporting address (i.e. r=user in its policy record) and a request for reports of such failures, the filter will send a structured report to that address containing details of the incident.

SenderHeaders (dataset)

Specifies an ordered list of header fields that should be searched to determine the sender of a message. This is mainly used when verifying a message to determine the origin domain, particularly for doing domain policy queries. By default, the DKIM library's internal list is used, which consists solely of the "From" header field.

SenderMacro (string)

Use the milter macro string to determine the sender of the message. (Experimental feature not enabled for this installation.)

SendReports (Boolean)

If true, when a signature verification fails and the signing site advertises a reporting address (i.e. r=user in its policy record) and a request for reports of such failures, the filter will send a structured report to that address containing details needed to reproduce the problem.

SetupPolicyScript (string)

Gives the name of a Lua script that should be run once all header fields for a message have arrived. The script has access to all of the headers and connection information and can request DKIM verification or signing based on that information. See opendkim-lua(3) for details.

SignatureAlgorithm (string)

Selects the signing algorithm to use when generating signatures. Use 'dkim-filter -V' to see the list of supported algorithms. The default is rsa-sha256 if it is available, otherwise it will be rsa-sha1.

SignatureTTL (integer)

Sets the time-to-live, in seconds, of signatures generated by the filter. If not set, no expiration time is added to signatures.

SignHeaders (dataset)

Specifies the set of headers that should be included when generating signatures. If the list omits any header that is mandated by the DKIM specification, those headers are implicitly added. By default, those headers listed in the DKIM specification as "SHOULD" be signed will be signed by the filter. Specifying a list here replaces that list entirely. See the OmitHeaders configuration option for more information.

SigningTable (dataset)

Defines a table used to select one or more signatures to apply to a message based on the address found in the From: header field. Keys in this table vary depending on the type of table used; values in this data set should refer to a name found in the KeyTable (see above) that identifies which key should be used in generating the signature.

If this table specifies a regular expression file ("refile"), then the keys are wildcard patterns that are matched against the address found in the From: header field. Entries are checked in the order in which they appear in the file.

For all other database types, the full user@host is checked first, then simply host, then user@.domain (with all superdomains checked in sequence, so "foo.example.com" would first check "user@foo.example.com", then "user@.example.com", then "user@.com"), then .domain, then user@*, and finally *.

In any case, only the first match is applied, unless MultipleSignatures is enabled in which case all matches are applied.

Socket (string)

Specifies the socket that should be established by the filter to receive connections from sendmail(8) in order to provide service. socketspec is in one of two forms: local:path, which creates a UNIX domain socket at the specified path, or inet:port[@host], which creates a TCP socket on the specified port. If the host is not given as either a hostname or an IP address, the socket will be listening on all interfaces. This option is mandatory either in the configuration file or on the command line.

Statistics (dataset)

This specifies a data set in which to store DKIM operation totals per domain. The data set must be initialized before the filter can use it. See opendkim-stats(8) for details about initialization, what data are recorded and how to read the current totals. Currently the only allowed data set type for this feature is "db". (feature is experimental)

StrictTestMode (Boolean)

Selects strict CRLF mode during testing (see the -t command line flag in the opendkim(8) man page); messages for which all header fields and body lines are not CRLF-terminated are considered malformed and will produce an error.

SubDomains (Boolean)

Sign subdomains of those listed by the Domain parameter as well as the actual domains.

Syslog (Boolean)

Log via calls to syslog(3) any interesting activity.

SyslogFacility (string)

Log via calls to syslog(3) using the named facility. The facility names are the same as the ones allowed in syslog.conf(5). The default is "mail".

SyslogSuccess (Boolean)

Log via calls to syslog(3) additional entries indicating successful signing or verification of messages.

TemporaryDirectory (string)

Specifies the directory in which temporary canonicalization files should be written. The default is to use the libdkim default location, currently /var/tmp.

TestPublicKeys (string)

Names a file from which public keys should be read. Intended for use only during automated testing.

TrustAnchorFile (string)

Specifies a file from which trust anchor data should be read when doing DNS queries and applying the DNSSEC protocol. See the Unbound documentation at http://unbound.net for the expected format of this file.

TrustSignaturesFrom (dataset)

This value consists of a set of domains that are considered trustworthy in terms of third-party signatures. That is, if a message arrives with a signature from a domain that doesn't match the domain in the From: header, this setting determines whether or not that signature will be trusted. If this value is undefined, all signatures are trusted.

UMask (integer)

Requests a specific permissions mask to be used for file creation. This only really applies to creation of the socket when Socket specifies a UNIX domain socket, and to the PidFile (if any); temporary files are created by the mkstemp(3) function that enforces a specific file mode on creation regardless of the process umask. See umask(2) for more information.

UserID (string)

Attempts to become the specified userid before starting operations. The value is of the form userid[:group]. The process will be assigned all of the groups and primary group ID of the named userid unless an alternate group is specified.

VBR-Certifiers (string)

The default certifiers if not specified in X-VBR-Certifiers header field. (Experimental feature not enabled for this installation.)

VBR-TrustedCertifiers (string)

A colon or comma sparated list of trusted certifiers to accept when verifying VBR-Info headers. Under revision and may not be stable. (Experimental feature not enabled for this installation.)

VBR-Type (string)

This default VBR type if not specified in the X-VBR-Type header field. (Experimental feature not enabled for this installation.)

X-Header (Boolean)

Causes opendkim to add a header indicating the presence of this filter in the path of the message from injection to delivery. The product's name, version, and the job ID are included in the header's contents.

NOTES

When using DNS timeouts (see the DNSTimeout option above), be sure not to use a timeout that is larger than the timeout being used for interaction between sendmail and the filter. Otherwise, the MTA could abort a message while waiting for a reply from the filter, which in turn is still waiting for a DNS reply.

Features that involve specification of IPv4 addresses or CIDR blocks will use the inet_addr(3) function to parse that information. Users should be familiar with the way that function handles the non-trivial cases (for example, "192.0.2/24" and "192.0.2.0/24" are not the same thing).

VERSION

This man page covers version 2.1.3 of opendkim.

COPYRIGHT

Copyright (c) 2007, 2008, Sendmail, Inc. and its suppliers. All rights reserved.

Copyright (c) 2009, 2010, The OpenDKIM Project. All rights reserved.

SEE ALSO

opendkim(8), opendkim-lua(3), sendmail(8)

RFC4871 - DomainKeys Identified Mail

RFC5451 - Message Header Field for Indicating Message Authentication Status

RFC5617 - DKIM Author Domain Signing Practises