opendkim - DKIM signing and verifying filter for MTAs
opendkim [-A] [-b modes] [-c canon] [-d domain[,...]] [-D] [-e name]
[-f] [-F time] [-k keyfile] [-l] [-L min] [-n] [-o hdrlist] [-p
socketspec] [-P pidfile] [-Q] [-r] [-s selector] [-S signalg] [-t
testfiles] [-T secs] [-u userid[:group]] [-v] [-V] [-W] [-x configfile]
opendkim implements the DKIM standard for signing and verifying e-mail
messages on a per-domain basis.
opendkim uses the milter interface, originally distributed as part of
version 8.11 of sendmail(8), to provide DKIM signing and/or verifying
service for mail transiting a milter-aware MTA.
Most, if not all, of the command line options listed below can also be
set using a configuration file. See the -x option for details.
Many of the command line and configuration file parameters will refer
to a "dataset" as their values. This refers to a string that either
contains the list of desirable values, or to a file that contains them,
or (if enabled at compile time) a database containing the data.
Some data sets require that the value contain more than one entry. How
this is done depends on which data set type is used.
Which type is used depends on the format of the specification string.
Note that not all of these are necessarily supported for all
installations; most of them depend on the availability of a particular
third-party library at compile time.
a) If the string begins with "file:", then the remainder of the
string is presumed to refer to a flat file that contains
elements of the data set, one per line. If a line contains
whitespace-separated values, then the line is preusmed to define
a key and its corresponding value. Blank lines are ignored, and
the hash ("#") character denotes the start of a comment. If a
value contains multiple entri