Identifies a file of "peers" which identifies clients whose connections
should be accepted without processing by this filter. The
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").
Automatically re-start on failures. Use with caution; if the filter
fails instantly after it starts, this can cause a tight
Selects operating modes.
is a concatenation of characters which indicate which mode(s) of operation
are desired. Valid modes are
(verifier). The default is
Selects the canonicalization method to be used when signing messages.
When verifying, the message's DomainKey-Signature: header specifies
the canonicalization method. The recognized values are
as defined by the DomainKeys draft. The default is
Configuration control. See the CONFIGURATION section for details.
-d domain [,...]
A comma-separated list of domains whose mail should be signed by this
filter. Mail from other domains will be verified rather than being signed.
If the value of this parameter starts with a "/" character, it is assumed
to be a filename from which the domain list will be read, one per line, with
"#" characters indicating the beginning of a comment.
In either case, the domain name(s) may contain the special character "*"
which is treated as a wildcard character matching zero or more characters
in a domain name.
Sign subdomains of those listed by the
option as well as the actual domains.
forks and exits immediately, leaving the service running in the background.
This flag suppresses that behaviour so that it runs in the foreground.
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.
Includes on DomainKey signatures the list of headers that were included
in the signature. This makes the signature header larger by explicitly
listing the included headers, but this also allows verifying agents to
ignore headers that were added in transit.
Identifies a file of internal hosts whose mail should be signed rather
than verified. Entries in this file follow the same form as those of
option above. If not specified, the default of "127.0.0.1" is applied.
Identifies a file of "external" hosts which 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 this file follow the same form as those of
to be interpreted as the location of a key list, which is a file listing rules
for signing with multiple keys. The key list should contain a set of lines of
is a pattern to match against message senders (with the special character "*"
interpreted as "zero or more characters"), and
is the path to the PEM-formatted private key to be used for signing messages
which match the
The selector used in the signature will be the filename portion of
Log via calls to
any interesting activity.
-m mta [,...]
A comma-separated list of MTA names (a la the
DaemonPortOptions Name parameter) whose mail should be signed by this
filter. There is no default.
Defines a set of MTA-provided
which 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
is specified, the value of the macro must match the value specified
(matching is case-insensitive), otherwise the macro must be defined but
may contain any value. The list is empty by default.
-o header [,...]
A comma-separated list of headers which should not be signed. Ignored when
Specifies the socket that should be established by the filter to receive
in order to provide service.
is in one of two forms:
which creates a UNIX domain socket at the specified
which creates a TCP socket on the specified
is not given as either a hostname or an IP address, the socket will be
listening on all interfaces. This option is mandatory.
Writes the process ID of the filter, once started, to the filename given.
Requests that messages which fail verification be quarantined by the
MTA. (Requires a sufficiently recent version of the milter library.)
When a signature verification fails and the signing site advertises a
reporting address (i.e.
in its policy record), send a structured report to that address containing
details needed to reproduce the problem.
Gives the location of a PEM-formatted private key to be used for message
Defines the name of the selector to be used when signing messages.
specification for details.
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.
Attempts to be come the specified
before starting operations.
Requests that the filter consult a POP authentication database for IP
addresses that should be allowed for signing. The filter must be specially
compiled to enable this feature, since it adds a library dependency.
Print the version number and exit without doing anything else.
The value of the
switch is a comma-separated list of settings of the form
which defines what the filter should do with messages that produce
certain results. Each result and each action has a full name and an
abbreviated name. Either is accepted. Below, the abbreviated name appears
(bad) the signature found in the message did not verify successfully
against the message;
(dns) an error was encountered attempting to retrieve a public key from
(int) an internal error occurred;
(no) no signature was present on the message;
(miss) no signature was present on the message which claims to sign
(a) accept the message;
(d) discard the message;
(t) temp-fail the message;
(r) reject the message.
In the interests of minimal initial impact, the defaults for
and the default for the others is
A message will be verified unless it conforms to the signing criteria,
which are: (1) the domain on the From: address or Sender: address (if present)
must be listed by the
command line switch, and (2) the client connecting to the MTA must (a)
have authenticated, or (b) be listed in the file referenced by the
command line switch (or be in the default list for that option), or (c)
be connected to daemon port named by the
command line switch.
When signing a message, a
header will be prepended to the message. The signature is computed using
the private key provided. You must be running a version of
recent enough to be able to do header prepend operations (8.13.0 or later).
When verifying a message, an
header will be prepended to indicate the presence of a signature and whether
or not it could be validated against the body of the message using the
public key advertised by the sender's nameserver. The value of this header
can be used by mail user agents to sort or discard messages that were not
signed or could not be verified.
The following environment variable(s) can be used to adjust the behaviour
of this filter:
The directory to use when creating temporary files. The default is
When using DNS timeouts (see the
option above), be sure not to use a timeout that is larger than the timeout
being used for interaction between
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.
This man page covers version 1.0.0 of
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