1opendkim.conf(5) File Formats Manual opendkim.conf(5)
2
6 opendkim.conf - Configuration file for opendkim
7
10 /etc/opendkim.conf
11
14 opendkim(8) implements the DKIM specification for signing and verifying
15 e-mail messages on a per-domain basis. This file is its configuration
16 file.
17 Blank lines are ignored. Lines containing a hash ("#") character are
19 truncated at the hash character to allow for comments in the file.
20 Other content should be the name of a parameter, followed by white
22 space, followed by the value of that parameter, each on a separate
23 line.
24 For parameters that are Boolean in nature, only the first byte of the
26 value is processed. For positive values, the following are accepted:
27 "T", "t", "Y", "y", "1". For negative values, the following are
28 accepted: "F", "f", "N", "n", "0".
29 Many, but not all, of these parameters are also available as command
31 line options to opendkim(8). However, new parameters are generally not
32 added as command line options so the complete set of options is avail‐
33 able here, and thus use of the configuration file is encouraged. In
34 some future release, the set of available command line options is
35 likely to get trimmed.
36 See the opendkim(8) man page for details about how and when the config‐
38 uration file contents are reloaded.
39 Some of these parameters are listed as having a type of "dataset". See
41 the opendkim(8) man page for a description of such parameters.
42 Unless otherwise stated, Boolean values default to "false", integer
44 values default to 0, and string and dataset values default to being
45 undefined.
46
49 AllowSHA1Only (Boolean)
50 Permit verify mode when only SHA1 support is available. RFC6376
51 requires that verifiers implement both SHA1 and SHA256 support.
52 Setting this feature changes the absence of SHA256 support from
53 an error to a warning.
54 AlwaysAddARHeader (Boolean)
57 Add an "Authentication-Results:" header field even to unsigned
58 messages from domains with no "signs all" policy. The reported
59 DKIM result will be "none" in such cases. Normally unsigned
60 mail from non-strict domains does not cause the results header
61 field to be added.
62 AuthservID (string)
65 Sets the "authserv-id" to use when generating the Authentica‐
66 tion-Results: header field after verifying a message. The
67 default is to use the name of the MTA processing the message.
68 If the string "HOSTNAME" is provided, the name of the host run‐
69 ning the filter (as returned by the gethostname(3) function)
70 will be used.
71 AuthservIDWithJobID (Boolean)
74 If "true", requests that the authserv-id portion of the added
75 Authentication-Results: header fields contain the job ID of the
76 message being evaluated.
77 AutoRestart (Boolean)
80 Automatically re-start on failures. Use with caution; if the
81 filter fails instantly after it starts, this can cause a tight
82 fork(2) loop.
83 AutoRestartCount (integer)
86 Sets the maximum automatic restart count. After this number of
87 automatic restarts, the filter will give up and terminate. A
88 value of 0 implies no limit; this is the default.
89 AutoRestartRate (string)
92 Sets the maximum automatic restart rate. If the filter begins
93 restarting faster than the rate defined here, it will give up
94 and terminate. This is a string of the form n/t[u] where n is
95 an integer limiting the count of restarts in the given interval
96 and t[u] defines the time interval through which the rate is
97 calculated; t is an integer and u defines the units thus repre‐
98 sented ("s" or "S" for seconds, the default; "m" or "M" for min‐
99 utes; "h" or "H" for hours; "d" or "D" for days). For example,
100 a value of "10/1h" limits the restarts to 10 in one hour. There
101 is no default, meaning restart rate is not limited.
102 Background (Boolean)
105 Causes opendkim to fork and exits immediately, leaving the ser‐
106 vice running in the background. The default is "true".
107 BaseDirectory (string)
110 If set, instructs the filter to change to the specified direc‐
111 tory using chdir(2) before doing anything else. This means any
112 files referenced elsewhere in the configuration file can be
113 specified relative to this directory. It's also useful for
114 arranging that any crash dumps will be saved to a specific loca‐
115 tion.
116 BodyLengthDB (dataset)
119 Requests that opendkim include a "l=" body length tag when the
120 set contains any of the envelope recipient addresses. The
121 addresses presented are tested against the database in various
122 forms as described under the SigningTable setting (below). This
123 feature of the protocol exists to improve the likelihood that a
124 signature will survive transit through a mailing list server, as
125 they commonly append footers to messages. Note, however, that
126 this creates a potential security issue since someone could add
127 arbitrary text to the signed message and the signature would
128 still validate. See the DKIM specification for details.
129 BogusKey (string)
132 Instructs the filter to treat a passing signature associated
133 with a bogus (forged) key in a special way. Possible values are
134 neutral (return a "neutral" result), none (take no special
135 action) and fail (return a "fail" result; this is the default).
136 (Not enabled for this installation.)
137 CaptureUnknownErrors (Boolean)
140 When set, and on systems where MTA quarantine is available, the
141 filter will request quarantine of a message that results in an
142 internal error or resource exhaustion.
143 Canonicalization (string)
146 Selects the canonicalization method(s) to be used when signing
147 messages. When verifying, the message's DKIM-Signature: header
148 field specifies the canonicalization method. The recognized
149 values are relaxed and simple as defined by the DKIM specifica‐
150 tion. The default is simple. The value may include two differ‐
151 ent canonicalizations separated by a slash ("/") character, in
152 which case the first will be applied to the header and the sec‐
153 ond to the body.
154 ChangeRootDirectory (string)
157 Requests that the operating system change the effective root
158 directory of the process to the one specified here prior to
159 beginning execution. chroot(2) requires superuser access. A
160 warning will be generated if UserID is not also set.
161 ClockDrift (integer)
164 Sets the tolerance in seconds to be applied when determining
165 whether a signature was either expired or generated in the
166 future. The default is 300.
167 Diagnostics (Boolean)
170 Requests the inclusion of "z=" tags in signatures, which encode
171 the original header field set for use by verifiers when diagnos‐
172 ing verification failures. Not recommended for normal opera‐
173 tion.
174 DiagnosticDirectory (string)
177 Directory into which to write diagnostic reports when message
178 verification fails on a message bearing a "z=" tag. If not set
179 (the default), these files are not generated.
180 DisableCryptoInit (Boolean)
183 If set, skips initialization of the SSL library initialization
184 steps, which are normaly required in multi-threaded environ‐
185 ments. This assumes some other library opendkim is using will
186 do the required initialization and shutdown.
187 DNSConnect (Boolean)
190 Requests that the asynchronous resolver start using TCP immedi‐
191 ately rather than using UDP until TCP is actually needed. Does
192 not work with all resolvers.
193 DNSTimeout (integer)
196 Sets the DNS timeout in seconds. A value of 0 causes an infi‐
197 nite wait. The default is 5. Ignored if not using an asynchro‐
198 nous resolver package. See also the NOTES section below.
199 Domain (dataset)
202 A set of domains whose mail should be signed by this filter.
203 Mail from other domains will be verified rather than being
204 signed.
205 This parameter is not required if a SigningTable is in use; in
207 that case, the list of signed domains is implied by the lines in
208 that file.
209 This parameter is ignored if a KeyTable is defined.
211 DomainKeysCompat (boolean)
214 If set, backward compatibility with DomainKeys (RFC4870) key
215 records is enabled. When not set, such keys are considered to
216 be syntactically invalid. The default is "false".
217 DontSignMailTo (dataset)
220 A set of e-mail address, mail to which should never be signed by
221 the filter. Note that this is an "any" feature; if any one of
222 the recipients of the message matches a member of this list, the
223 message will not be signed.
224 EnableCoredumps (boolean)
227 On systems that have such support, make an explicit request to
228 the kernel to dump cores when the filter crashes for some rea‐
229 son. Some modern UNIX systems suppress core dumps during
230 crashes for security reasons if the user ID has changed during
231 the lifetime of the process. Currently only supported on Linux.
232 ExemptDomains (dataset)
235 Specifies a set of domains, mail from which should be ignored
236 entirely by the filter. This is similar to the PeerList setting
237 except that it bases its decision on the sender of the message
238 as identified from the header fields or other message data, not
239 the identity of the SMTP client sending the message.
240 ExternalIgnoreList (dataset)
243 Identifies a set of "external" hosts that may send mail through
244 the server as one of the signing domains without credentials as
245 such. This has the effect of suppressing the "external host
246 (hostname) tried to send mail as (domain)" log messages.
247 Entries in the data set should be of the same form as those of
248 the PeerList option below. The set is empty by default.
249 FinalPolicyScript (string)
252 Gives the name of a Lua script that should be run after the
253 entire message has been received. This can be used to enact
254 local policy decisions such as message rejection, quarantine,
255 rerouting, etc. based on signatures found on the message, the
256 results of attempts to verify them, and other properties of the
257 message or signatures. See opendkim-lua(3) for details. (Not
258 enabled for this installation.)
259 FixCRLF (Boolean)
262 Requests that the DKIM library convert bare CRs and LFs to CRLFs
263 during body canonicalization, anticipating that an MTA somewhere
264 before delivery will do that conversion anyway. The default is
265 to leave them as-is.
266 IdentityHeader (string)
269 This specifies the header field where an identity is stored.
270 (Experimental feature not enabled for this installation.)
271 IdentityHeaderRemove (Boolean)
274 Remove the IdentityHeader after signing. (Experimental feature
275 not enabled for this installation.)
276 IgnoreMalformedMail (boolean)
279 Silently passes malformed messages without alteration. This
280 includes messages that fail the RequiredHeaders check, if
281 enabled. The default is to pass those messages but add an
282 Authentication-Results field indicating that they were mal‐
283 formed.
284 Include (string)
287 Names a file to be opened and read as an additional configura‐
288 tion file. Nesting is allowed to a maximum of five levels.
289 InternalHosts (dataset)
292 Identifies a set internal hosts whose mail should be signed
293 rather than verified. Entries in this data set follow the same
294 form as those of the PeerList option below. If not specified,
295 the default of "127.0.0.1" is applied. Naturally, providing a
296 value here overrides the default, so if mail from 127.0.0.1
297 should be signed, the list provided here should include that
298 address explicitly.
299 KeepAuthResults (boolean)
302 Suppresses removal of Authentication-Results header fields con‐
303 taining DKIM results apparently added by this filter (usually
304 the result of a misconfiguration or a forgery).
305 KeepTemporaryFiles (boolean)
308 Instructs the filter to create temporary files containing the
309 header and body canonicalizations of messages that are signed or
310 verified. The location of these files can be set using the Tem‐
311 poraryDirectory parameter. Intended only for debugging verifi‐
312 cation problems.
313 KeyFile (string)
316 Gives the location of a PEM-formatted private key to be used for
317 signing all messages. Ignored if a KeyTable is defined.
318 KeyTable (dataset)
321 Gives the location of a file mapping key names to signing keys.
322 If present, overrides any KeyFile setting in the configuration
323 file. The data set named here maps each key name to three val‐
324 ues: (a) the name of the domain to use in the signature's "d="
325 value; (b) the name of the selector to use in the signature's
326 "s=" value; and (c) either a private key or a path to a file
327 containing a private key. If the first value consists solely of
328 a percent sign ("%") character, it will be replaced by the
329 apparent domain of the sender when generating a signature. If
330 the third value starts with a slash ("/") character, or "./" or
331 "../", then it is presumed to refer to a file from which the
332 private key should be read, otherwise it is itself a PEM-encoded
333 private key or a base64-encoded DER private key; a "%" in the
334 third value in this case will be replaced by the apparent domain
335 name of the sender. The SigningTable (see below) is used to
336 select records from this table to be used to add signatures
337 based on the message sender.
338 LDAPAuthMechanism (string)
341 Names the authentication mechanism to use when connecting to an
342 LDAP server. The default is the empty string, meaning "simple"
343 authentication should be done.
344 LDAPAuthName (string)
347 Specifies the authenticating name to use when using SASL to
348 authenticate to an LDAP server. Requires SASL support be
349 installed on the local system. There is no default.
350 LDAPAuthRealm (string)
353 Specifies the authentication realm to use when using SASL to
354 authenticate to an LDAP server. Requires SASL support be
355 installed on the local system. There is no default.
356 LDAPAuthUser (string)
359 Specifies the authenticating user to use when using SASL to
360 authenticate to an LDAP server. Requires SASL support be
361 installed on the local system. There is no default.
362 LDAPBindPassword (string)
365 Specifies the password to use when conducting an LDAP "bind"
366 operation. There is no default.
367 LDAPBindUser (string)
370 Specifies the user ID to use when conducting an LDAP "bind"
371 operation. There is no default.
372 LDAPDisableCache (Boolean)
375 Suppresses creation of a local cache in front of LDAP queries.
376 LDAPKeepaliveIdle (integer)
379 Sets the number of seconds a connection to an LDAP server needs
380 to remain idle before TCP starts sending keepalive probes. If
381 not specified, the LDAP library default is used.
382 LDAPKeepaliveInterval (integer)
385 Sets the interval in seconds between TCP keepalive probes. If
386 not specified, the LDAP library default is used.
387 LDAPKeepaliveProbes (integer)
390 Sets the maximum number of keepalive probes TCP should send
391 before abandoning the connection. If not specified, the LDAP
392 library default is used.
393 LDAPTimeout (integer)
396 Sets the time in seconds after which an LDAP operation should be
397 abandoned. The default is 5.
398 LDAPUseTLS (Boolean)
401 Indicates whether or not a TLS connection should be established
402 when contacting an LDAP server. The default is "False".
403 LogResults (boolean)
406 If logging is enabled (see Syslog below), requests that the
407 results of evaluation of all signatures that were at least
408 partly intact (i.e., the "d=", "s=", and "b=" tags could be
409 extracted).
410 LogWhy (boolean)
413 If logging is enabled (see Syslog below), issues very detailed
414 logging about the logic behind the filter's decision to either
415 sign a message or verify it. The logic behind the decision is
416 non-trivial and can be confusing to administrators not familiar
417 with its operation. A description of how the decision is made
418 can be found in the OPERATIONS section of the opendkim(8) man
419 page. This causes a large increase in the amount of log data
420 generated for each message, so it should be limited to debugging
421 use and not enabled for general operation.
422 MacroList (dataset)
425 Defines a set of MTA-provided macros that should be checked to
426 see if the sender has been determined to be a local user and
427 therefore whether or not the message should be signed. If a
428 value is specified matching a macro name in the data set, the
429 value of the macro must match a value specified (matching is
430 case-sensitive), otherwise the macro must be defined but may
431 contain any value. The set is empty by default, meaning macros
432 are not considered when making the sign-verify decision. The
433 general format of the value is value1[|value2[|...]]; if one or
434 more value is defined then the macro must be set to one of the
435 listed values, otherwise the macro must be set but can contain
436 any value.
437 In order for the macro and its value to be available to the fil‐
439 ter for checking, the MTA must send it during the protocol
440 exchange. This is either accomplished via manual configuration
441 of the MTA to send the desired macros or, for MTA/filter combi‐
442 nations that support the feature, the filter can request those
443 macros that are of interest. The latter is a feature negotiated
444 at the time the filter receives a connection from the MTA and
445 its availability depends upon the version of milter used to com‐
446 pile the filter and the version of the MTA making the connec‐
447 tion.
448 This data set must be of type "file" or "csl".
450 MaximumHeaders (integer)
452 Defines the maximum number of bytes the header block of a mes‐
453 sage may consume before the filter will reject the message.
454 This mitigates a denial-of-service attack in which a client con‐
455 nects to the MTA and begins feeding an unbounded number of
456 header fields of arbitrary size; since the filter keeps a cache
457 of these, the attacker could cause the filter to allocate an
458 unspecified amount of memory. The default is 65536; a value of
459 0 removes the limit.
460 MaximumSignaturesToVerify (integer)
463 Defines the maximum number of signatures on a message for which
464 verification should be conducted. The default is three. Signa‐
465 tures are selected from the top of the message downward. If
466 TrustSignaturesFrom is set, signatures from domains in that data
467 set are always verified, which may consume part or all of, or
468 even exceed, this limit.
469 MaximumSignedBytes (integer)
472 Specifies the maximum number of bytes of message body to be
473 signed. Messages shorter than this limit will be signed in
474 their entirety. Setting this value implies use of BodyLengthDB
475 for all addresses.
476 MilterDebug (integer)
479 Sets the debug level to be requested from the milter library.
480 The default is 0.
481 Minimum (string)
484 Instructs the verification code to fail messages for which a
485 partial signature was received. There are three possible for‐
486 mats: min indicating at least min bytes of the message must be
487 signed (or if the message is smaller than min then all of it
488 must be signed); min% requiring that at least min percent of the
489 received message must be signed; and min+ meaning there may be
490 no more than min bytes of unsigned data appended to the message
491 for it to be considered valid.
492 MinimumKeyBits (integer)
495 Establishes a minimum key size for acceptable signatures. Sig‐
496 natures with smaller key sizes, even if they otherwise pass DKIM
497 validation, will me marked as invalid. The default is 1024,
498 which accepts all signatures. A value of 0 causes the default
499 to be used.
500 Mode (string)
503 Selects operating modes. The string is a concatenation of char‐
504 acters that indicate which mode(s) of operation are desired.
505 Valid modes are s (signer) and v (verifier). The default is sv
506 except in test mode (see the opendkim(8) man page) in which case
507 the default is v. When signing mode is enabled, one of the fol‐
508 lowing combinations must also be set: (a) Domain, KeyFile,
509 Selector, no KeyTable, no SigningTable; (b) KeyTable, Sign‐
510 ingTable, no Domain, no KeyFile, no Selector; (c) KeyTable,
511 SetupPolicyScript, no Domain, no KeyFile, no Selector.
512 MTA (dataset)
515 A set of MTA names (a la the sendmail(8) DaemonPortOptions Name
516 parameter) whose mail should be signed by this filter. There is
517 no default, meaning MTA name is not considered when making the
518 sign-verify decision.
519 MTACommand (string)
522 Specifies the path to an executable to be used for sending mail
523 such as that generated by SendReports. The default is
524 /usr/sbin/sendmail. The executable should accept typical send‐
525 mail(8) command line options "-t" (take addresses from message
526 body) and "-f" (set envelope sender), accept the new message on
527 its standard input, and return a non-zero exit status on any
528 error.
529 MultipleSignatures (Boolean)
532 Allow addition of multiple signatures when a signing table is in
533 use. See SigningTable for more information.
534 MustBeSigned (dataset)
537 Specifies a set of header fields that, if present, must be cov‐
538 ered by the DKIM signature when verifying a message. If a
539 header field in this set is present in the message and is not
540 signed, the filter will treat even an otherwise valid signature
541 as invalid. The default is an empty list.
542 Nameservers (string)
545 Provides a comma-separated list of IP addresses that are to be
546 used when doing DNS queries to retrieve DKIM keys, VBR records,
547 etc. These override any local defaults built in to the resolver
548 in use, which may be defined in /etc/resolv.conf or hard-coded
549 into the software.
550 NoHeaderB (Boolean)
553 If set, this feature suppresses the use of "header.b" tags in
554 added Authentication-Results header fields. The default is
555 "false", which means those tags will be applied.
556 OmitHeaders (dataset)
559 Specifies a set of header fields that should be omitted when
560 generating signatures. If an entry in the list names any header
561 field that is mandated by the DKIM specification, the entry is
562 ignored. A set of header fields is listed in the DKIM specifi‐
563 cation (RFC6376, Section 5.4) as "SHOULD NOT" be signed; the
564 default list for this parameter contains those fields (Return-
565 Path, Received, Comments, Keywords, Bcc, Resent-Bcc and DKIM-
566 Signature). To omit no headers, simply use the string "." (or
567 any string that will match no header field names). Specifying a
568 list with this parameter replaces the default entirely, unless
569 one entry is "*" in which case the list is interpreted as a
570 delta to the default; for example, "*,+foobar" will use the
571 entire default list plus the name "foobar", while "*,-Bcc" would
572 use the entire default list except for the "Bcc" entry.
573 On-BadSignature (string)
576 Selects the action to be taken when a signature fails to vali‐
577 date. Possible values (with abbreviated forms in parentheses):
578 accept (a) accept the message; discard (d) discard the message;
579 quarantine (q) quarantine the message; reject (r) reject the
580 message; tempfail (t) temp-fail the message. The default is
581 accept. Note that the "t" (testing) flag in a DKIM key bypasses
582 this behaviour; a bad signature that references a testing flag
583 will still be delivered, though the added Authentication-Results
584 field will indicate both the failed result and the test mode so
585 that consumers of the message can take appropriate action.
586 On-Default (string)
589 Selects the action to be taken when any verification or internal
590 error of any kind is encountered. This is processed before the
591 other "On-" values so it can be used as a blanket setting fol‐
592 lowed by specific overrides.
593 On-DNSError (string)
596 Selects the action to be taken when a transient DNS error is
597 encountered. Possible values are the same as those for On-
598 BadSignature. The default is tempfail.
599 On-InternalError (string)
602 Selects the action to be taken when an internal error of some
603 kind is encountered. Possible values are the same as those for
604 On-BadSignature. The default is tempfail.
605 On-KeyNotFound (string)
608 Selects the action to be taken when the key referenced by a sig‐
609 nature is not present in the DNS. Possible values are the same
610 as those for On-BadSignature. The default is accept.
611 On-NoSignature (string)
614 Selects the action to be taken when a message arrives unsigned.
615 Possible values are the same as those for On-BadSignature. The
616 default is accept.
617 On-Security (string)
620 Selects the action to be taken when a message arrives containing
621 properties that may be a security concern. Possible values are
622 the same as those for On-BadSignature. The default is tempfail.
623 On-SignatureError (string)
626 Selects the action to be taken when a message cannot be signed
627 because of issues with the message or the key provided for sign‐
628 ing. Possible values are the same as those for On-BadSignature.
629 The default is reject.
630 OversignHeaders (dataset)
633 Specifies a set of header fields that should be included in all
634 signature header lists (the "h=" tag) once more than the number
635 of times they were actually present in the signed message. The
636 set is empty by default. The purpose of this, and especially of
637 listing an absent header field, is to prevent the addition of
638 important fields between the signer and the verifier. Since the
639 verifier would include that header field when performing verifi‐
640 cation if it had been added by an intermediary, the signed mes‐
641 sage and the verified message were different and the verifica‐
642 tion would fail. Note that listing a field name here and not
643 listing it in the SignHeaders list is likely to generate invalid
644 signatures.
645 PeerList (dataset)
648 Identifies a set of "peers" that identifies clients whose con‐
649 nections should be accepted without processing by this filter.
650 The set should contain on each line a hostname, domain name
651 (e.g. ".example.com"), IP address, an IPv6 address (including an
652 IPv4 mapped address), or a CIDR-style IP specification (e.g.
653 "192.168.1.0/24"). An entry beginning with a bang ("!") charac‐
654 ter means "not", allowing exclusions of specific hosts that are
655 otherwise members of larger sets. Host and domain names are
656 matched first, then the IP or IPv6 address depending on the con‐
657 nection type. More precise entries are preferred over less pre‐
658 cise ones, i.e. "192.168.1.1" will match before
659 "!192.168.1.0/24". The text form of IPv6 addresses will be
660 forced to lowercase when queried (RFC5952), so the contents of
661 this data set should also use lowercase. The IP address portion
662 of an entry may optionally contain square brackets; both forms
663 (with and without) will be checked.
664 PidFile (string)
667 Specifies the path to a file that should be created at process
668 start containing the process ID.
669 POPDBFile (dataset)
672 Requests that the filter consult a set for IP addresses that
673 should be allowed for signing. This feature was designed for
674 POP-before-SMTP datastores. (Not enabled for this installa‐
675 tion.)
676 Quarantine (Boolean)
679 Requests that messages which fail verification be quarantined by
680 the MTA. (Requires a sufficiently recent version of the milter
681 library.)
682 QueryCache (Boolean)
685 Instructs the DKIM library to maintain its own local cache of
686 keys and policies retrieved from DNS, rather than relying on the
687 nameserver for caching service. Useful if the nameserver being
688 used by the filter is not local.
689 RedirectFailuresTo (address)
693 Messages bearing signatures that failed to verify are redirected
694 to the specified address. The original envelope recipient set
695 is recorded in the header before redirection occurs. By
696 default, no redirection is done.
697 RemoveARAll (Boolean)
700 Removes all Authentication-Results: header fields that also sat‐
701 isfy the requirements of RemoveARFrom below. By default, only
702 those containing a DKIM result are removed.
703 RemoveARFrom (dataset)
706 Defines a set of hostnames whose Authentication-Results: header
707 fields should be removed before the message is passed for deliv‐
708 ery. By default only those header fields matching the local
709 host's canonical name will be removed. Matching is only done on
710 full hostnames (e.g. "host.example.com") or on domain names
711 (e.g. ".example.com").
712 RemoveOldSignatures (Boolean)
715 Removes all existing signatures when operating in signing mode.
716 ReplaceHeaders (data set)
719 Defines a set of header fields that should be affected by the
720 text replacement rules defined by the ReplaceRules setting. By
721 default, all header fields are included. (Experimental feature
722 not enabled for this installation.)
723 ReplaceRules (string)
726 Specifies a file containing a list of text replacement rules
727 that are applied to the message header fields to replace certain
728 content expected to be changed as the message passes through
729 local MTAs. This can be used to accommodate expected changes
730 such as are made to From: fields by MTA "masquerade" features.
731 Each entry in the file consists of a POSIX regular expression,
732 followed by a tab (ASCII 9), followed by the text that should be
733 used to replace the text matching the expression. The '#' char‐
734 acter denotes the beginning of a comment and text from that
735 point on in a single line is ignored. Blank lines are also
736 skipped. (Experimental feature not enabled for this installa‐
737 tion.)
738 ReportAddress (string)
741 Specifies the string to use in the From: header field for outgo‐
742 ing reports (see SendReports below). If not specified, the exe‐
743 cuting user and local hostname will be used to construct the
744 address.
745 ReportBccAddress (string)
748 Specifies address(es) to include in a Bcc: header field on out‐
749 going reports (see SendReports below). If multiple addresses are
750 required, they should be comma separated.
751 RequestReports (boolean)
754 When signing, includes a request for signature evaluation fail‐
755 ures in the signature. (See RFC6651 for details.)
756 RequiredHeaders (boolean)
759 Checks all messages for compliance with RFC5322 header field
760 count requirements. Non-compliant messages are rejected.
761 RequireSafeKeys (boolean)
764 When reading a key file, a message will be logged if the key
765 file has the read or write bit set other than for the owner or
766 for a group that the executing process is in. With this feature
767 set to "true", the filter will further consider this an error
768 and refuse to make use of the file's contents. The default is
769 "true".
770 ResignAll (boolean)
773 Where ResignMailTo triggers a re-signing action, this flag indi‐
774 cates whether or not all mail should be signed (if set) versus
775 only verified mail being signed (if not set). The default is
776 "false". (Experimental feature not enabled for this installa‐
777 tion.)
778 ResignMailTo (dataset)
781 Checks each message recipient against the specified dataset for
782 a matching record. The full address is checked in each case,
783 then the hostname, then each domain preceded by ".". If there
784 is a match, the value returned is presumed to be the name of a
785 key in the KeyTable (if defined) to be used to re-sign the mes‐
786 sage in addition to verifying it. If there is a match without a
787 KeyTable, the default key is applied. (Experimental feature not
788 enabled for this installation.)
789 ResolverConfiguration (string)
792 Provides the given string as configuration information to the
793 underlying resolver. For the standard UNIX resolver, this is
794 unused; for Unbound, the string contains a filename that is con‐
795 sidered to be a configuration file. There is no default.
796 ResolverTracing (Boolean)
799 Requests resolver tracing features be enabled, if available.
800 The effect of this depends on how debugging features of the
801 resolver might be implemented. Currently only effective with
802 the OpenDKIM asynchronous resolver library.
803 ScreenPolicyScript (string)
806 Gives the name of a Lua script that should be run after all of
807 the header fields have been processed for a message; in particu‐
808 lar, this is useful after all DKIM signatures have been detected
809 and initial evaluation has been done. The script has access to
810 all of the header fields and connection information and can that
811 certain signatures be ignored based on that information. See
812 opendkim-lua(3) for details. (Not enabled for this installa‐
813 tion.)
814 SelectCanonicalizationHeader (string)
817 Defines a header field name which, if present, adjusts which
818 canonicalization will be used to generate an outgoing signature.
819 Overrides the Canonicalization setting if the header field is
820 present. The default is "X-Canonicalization".
821 Selector (string)
824 Defines the name of the selector to be used when signing mes‐
825 sages. See the DKIM specification for details. Used only when
826 signing with a single key; see the SigningTable parameter below
827 for more information.
828 This parameter is ignored if a KeyTable is defined.
830 SenderHeaders (dataset)
833 Specifies an ordered list of header fields that should be
834 searched to determine the sender of a message. The first header
835 field found is the one whose value is used. This is mainly used
836 when signing for deciding which signing request(s) to make. By
837 default, the "From" header field is the only one checked. See
838 the OmitHeaders setting for a description of possible values.
839 SenderMacro (string)
842 Use the milter macro string to determine the sender of the mes‐
843 sage. (Experimental feature not enabled for this installation.)
844 SendReports (Boolean)
847 If true, when a signature verification fails and the signature
848 included a reporting request ("r=y") and the signing domain
849 advertises a reporting address (i.e. ra=user) in a reporting
850 record in the DNS, the filter will send a structured report to
851 that address containing details needed to reproduce the problem.
852 See RFC6651 for a complete description of this mechanism.
853 SetupPolicyScript (string)
856 Gives the name of a Lua script that should be run once all
857 header fields for a message have arrived. The script has access
858 to all of the header fields and connection information and can
859 request DKIM verification or signing based on that information.
860 See opendkim-lua(3) for details. (Not enabled for this installa‐
861 tion.)
862 SignatureAlgorithm (string)
865 Selects the signing algorithm to use when generating signatures.
866 Use 'opendkim -V' to see the list of supported algorithms. The
867 default is rsa-sha256 if it is available, otherwise it will be
868 rsa-sha1.
869 SignatureTTL (integer)
872 Sets the time-to-live, in seconds, of signatures generated by
873 the filter. If not set, no expiration time is added to signa‐
874 tures.
875 SignHeaders (dataset)
878 Specifies the set of header fields that should be included when
879 generating signatures. If the list omits any header field that
880 is mandated by the DKIM specification, those fields are implic‐
881 itly added. By default, those fields listed in the DKIM speci‐
882 fication as "SHOULD" be signed (RFC6376, Section 5.4) will be
883 signed by the filter. See the OmitHeaders configuration option
884 for more information about the format and interpretation of this
885 field.
886 SigningTable (dataset)
889 Defines a table used to select one or more signatures to apply
890 to a message based on the address found in the From: header
891 field. Keys in this table vary depending on the type of table
892 used; values in this data set should include one field that con‐
893 tains a name found in the KeyTable (see above) that identifies
894 which key should be used in generating the signature, and an
895 optional second field naming the signer of the message that will
896 be included in the "i=" tag in the generated signature. Note
897 that the "i=" value will not be included in the signature if it
898 conflicts with the signing domain (the "d=" value).
899 If the first field contains only a "%" character, it will be
901 replaced by the domain found in the From: header field. Simi‐
902 larly, within the optional second field, any "%" character will
903 be replaced by the domain found in the From: header field.
904 If this table specifies a regular expression file ("refile"),
906 then the keys are wildcard patterns that are matched against the
907 address found in the From: header field. Entries are checked in
908 the order in which they appear in the file.
909 For all other database types, the full user@host is checked
911 first, then simply host, then user@.domain (with all superdo‐
912 mains checked in sequence, so "foo.example.com" would first
913 check "user@foo.example.com", then "user@.example.com", then
914 "user@.com"), then .domain, then user@*, and finally *.
915 In any case, only the first match is applied, unless MultipleS‐
917 ignatures is enabled in which case all matches are applied.
918 SMTPURI (string)
921 Specifies a URI (e.g., "smtp://localhost") to which mail should
922 be sent via SMTP when notifications are generated. (Not enabled
923 for this installation.)
924 Socket (string)
927 Specifies the socket that should be established by the filter to
928 receive connections from sendmail(8) in order to provide ser‐
929 vice. socketspec is in one of two forms: local:path, which cre‐
930 ates a UNIX domain socket at the specified path, or
931 inet:port[@host] or inet6:port[@host] which creates a TCP socket
932 on the specified port and in the specified protocol family. If
933 the host is not given as either a hostname or an IP address, the
934 socket will be listening on all interfaces. A literal IP
935 address must be enclosed in square brackets. This option is
936 mandatory either in the configuration file or on the command
937 line.
938 SoftStart (Boolean)
941 If set, the inability to connect and authenticate to an LDAP or
942 SQL server will not prevent the filter from starting, and recon‐
943 nections will be attempted for each query. The default is
944 "False".
945 SoftwareHeader (Boolean)
948 Causes opendkim to add an "DKIM-Filter" header field indicating
949 the presence of this filter in the path of the message from
950 injection to delivery. The product's name, version, and the job
951 ID are included in the header field's contents. Note that the
952 header field is not added if the Mode setting causes the message
953 to be ignored (e.g., if only signing mode is enabled and the
954 configuration causes the message not to be signed, or only ver‐
955 ify mode is enabled and configuration would otherwise have
956 caused the message to be signed, then it will not have this
957 header field added).
958 Statistics (filename)
961 This specifies a file in which to store DKIM transaction statis‐
962 tics. See opendkim-stats(8) for a mechanism to parse the file's
963 contents, and opendkim-importstats() for a mechanism to trans‐
964 late the file's contents into SQL database insertions. (Experi‐
965 mental feature not enabled for this installation.)
966 StatisticsName (string)
969 Defines the name to be used as the reporting host in statistics
970 logs. By default, the local host's name returned by gethost‐
971 name(3) is used. (Experimental feature not enabled for this
972 installation.)
973 StatisticsPrefix (string)
976 When AnonymousStatistics is enabled, this string may be speci‐
977 fied and will be prepended to all data before hashing for more
978 complete anonymization. This means two records from different
979 sources referencing the same source will still produce different
980 hashes, meaning such correlation is now only possible within the
981 data from a single repoter.
982 StrictHeaders (Boolean)
985 If set, instructs the DKIM library to refuse processing of a
986 message if the header field count does not conform to RFC5322
987 Section 3.6.
988 StrictTestMode (Boolean)
991 Selects strict CRLF mode during testing (see the -t command line
992 flag in the opendkim(8) man page); messages for which all header
993 fields and body lines are not CRLF-terminated are considered
994 malformed and will produce an error.
995 SubDomains (Boolean)
998 Sign subdomains of those listed by the Domain parameter as well
999 as the actual domains.
1000 Syslog (Boolean)
1003 Log via calls to syslog(3) any interesting activity.
1004 SyslogFacility (string)
1007 Log via calls to syslog(3) using the named facility. The facil‐
1008 ity names are the same as the ones allowed in syslog.conf(5).
1009 The default is "mail".
1010 SyslogSuccess (Boolean)
1013 Log via calls to syslog(3) additional entries indicating suc‐
1014 cessful signing or verification of messages.
1015 TemporaryDirectory (string)
1018 Specifies the directory in which temporary canonicalization
1019 files should be written. The default is to use the libdkim
1020 default location, currently /tmp.
1021 TestDNSData (data set)
1024 Provides a data set whose keys will be treated as DNS record
1025 names and values as TXT record contents. Intended for use dur‐
1026 ing automated testing.
1027 TestPublicKeys (string)
1030 Names a file from which public keys should be read. Intended
1031 for use only during automated testing.
1032 TrustAnchorFile (string)
1035 Specifies a file from which trust anchor data should be read
1036 when doing DNS queries and applying the DNSSEC protocol. This
1037 is currently ignored unless the underlying library is compiled
1038 to use Unbound; see the documentation at at http://unbound.net
1039 for the expected format of this file.
1040 TrustSignaturesFrom (dataset)
1043 This value consists of a set of domains that are considered
1044 trustworthy in terms of third-party signatures. That is, if a
1045 message arrives with a signature from a domain that doesn't
1046 match the domain in the From: header, this setting determines
1047 whether or not that signature will be trusted. If this value is
1048 undefined, all signatures are trusted.
1049 UMask (integer)
1052 Requests a specific permissions mask to be used for file cre‐
1053 ation. This only really applies to creation of the socket when
1054 Socket specifies a UNIX domain socket, and to the PidFile (if
1055 any); temporary files are created by the mkstemp(3) function
1056 that enforces a specific file mode on creation regardless of the
1057 process umask. See umask(2) for more information.
1058 UnprotectedKey (string)
1061 Instructs the filter to treat a passing signature associated
1062 with a key found in an insecure (i.e. not protected by DNSSEC)
1063 DNS record in a special way. Possible values are neutral
1064 (return a "neutral" result), none (take no special action; this
1065 is the default) and fail (return a "fail" result). (Not enabled
1066 for this installation.)
1067 UserID (string)
1070 Attempts to become the specified userid before starting opera‐
1071 tions. The value is of the form userid[:group]. The process
1072 will be assigned all of the groups and primary group ID of the
1073 named userid unless an alternate group is specified.
1074 VBR-Certifiers (string)
1077 The default certifiers if not specified in X-VBR-Certifiers
1078 header field. (Experimental feature not enabled for this
1079 installation.)
1080 VBR-PurgeFields (string)
1083 If set, arranges to remove X-VBR-Certifiers and X-VBR-Type
1084 fields on messages prior to sending them. (Experimental feature
1085 not enabled for this installation.)
1086 VBR-TrustedCertifiers (string)
1089 A colon or comma sparated list of trusted certifiers to accept
1090 when verifying VBR-Info header field. (Experimental feature not
1091 enabled for this installation.)
1092 VBR-TrustedCertifiersOnly (Boolean)
1095 By default, the certifiers that are in both the trusted certi‐
1096 fiers list (above) and those in the message's VBR-Info header
1097 field will be checked for vouching. With this option set, the
1098 trusted certifiers will be checked and the ones claimed by the
1099 message will be ignored. (Experimental feature not enabled for
1100 this installation.)
1101 VBR-Type (string)
1104 This default VBR type if not specified in the X-VBR-Type header
1105 field. (Experimental feature not enabled for this installa‐
1106 tion.)
1107 WeakSyntaxChecks (Boolean)
1110 Requests that the library continue processing messages even if
1111 syntax errors are discovered early in message analysis. This
1112 means, for example, that a signed message with a mangled From:
1113 field will still proceed to verification even if the author's
1114 domain could not be determined.
1115
1118 When using DNS timeouts (see the DNSTimeout option above), be sure not
1119 to use a timeout that is larger than the timeout being used for inter‐
1120 action between sendmail and the filter. Otherwise, the MTA could abort
1121 a message while waiting for a reply from the filter, which in turn is
1122 still waiting for a DNS reply.
1123 Features that involve specification of IPv4 addresses or CIDR blocks
1125 will use the inet_addr(3) function to parse that information. Users
1126 should be familiar with the way that function handles the non-trivial
1127 cases (for example, "192.0.2/24" and "192.0.2.0/24" are not the same
1128 thing).
1129
1131 /etc/opendkim.conf
1132 Default location of this file.
1133
1135 This man page covers version 2.11.0 of opendkim.
1136
1139 Copyright (c) 2007, 2008, Sendmail, Inc. and its suppliers. All rights
1140 reserved.
1141 Copyright (c) 2009-2015, The Trusted Domain Project. All rights
1143 reserved.
1144
1146 opendkim(8), opendkim-lua(3), sendmail(8)
1147 RFC5451 - Message Header Field for Indicating Message Authentication
1149 Status
1150 RFC5617 - DKIM Author Domain Signing Practises
1152 RFC5965 - An Extensible Format for Email Feedback Reports
1154 RFC6008 - Authentication-Results Registration for Differentiating among
1156 Cryptographic Results
1157 RFC6376 - DomainKeys Identified Mail
1159 RFC6651 - Extensions to DomainKeys Identified Mail (DKIM) for Failure
1161 Reporting
1162 The Trusted Domain Project opendkim.conf(5)