Ubuntu Manpage: greylist.conf - milter-greylist configuration file

Provided by: milter-greylist_4.6.4-4_amd64

NAME

       greylist.conf - milter-greylist configuration file

DESCRIPTION

       greylist.conf configures milter-greylist(8) operation. The format is simple: each line contains a keyword
       and optional arguments. Any line starting with a # is considered as a comment and is ignored. Blank lines
       are  ignored  as well. Comments at the end of lines are accepted in some situations, but do not take them
       as granted.  A statement can be continued on the next line by  using  a  backslash.  Anything  after  the
       backslash will be ignored.

WHITELIST

The primary use of greylist.conf is to setup milter-greylist(8) whitelist. It also offers a handy
blacklist feature. Access-lists (ACL) are used to do that. ACL enable the administrator to specify
complex conditions on sender IP, sender DNS address, sender e-mail address, and recipient e-mail address.
If support for DNSRBL was built-in, it is even possible to use DNSRBL in ACL.

An access-list entry starts with the racl keyword followed by an optional id quoted string, then the
greylist, whitelist, blacklist, or continue keyword, and by any set of the following clauses: addr,
domain, from, rawfrom, rcpt, rcptcount, helo, sm_macro, time, auth, tls, spf (if build with SPF support),
geoip (if build with GeoIP support), p0f (if build with p0f support), ldapcheck (if build with --with-
openldap), urlcheck (if built with --with-libcurl), dnsrbl (if built with --enable-dnsrbl), and nsupdate
(if supported by the DNS resolver). A message will match an ACL entry when it complies with all of its
clauses.

The greylist, whitelist, and blacklist keywords will cause the message to be respectively greylisted,
accepted or rejected if all ACL clauses match, and ACL evaluation is terminated there. If an ACL with
continue keyword does match, nothing is decided and next ACL are evaluated.

Clauses can be negated, by prefixing them by the not keyword. Here is the detail of all possible clauses.

addr This clause is used to specify a netblock of source IP addresses. The syntax is an IP address
followed by a slash and a CIDR netmask. Here is an example:

racl whitelist addr 127.0.0.0/8
racl whitelist addr 192.168.3.0/24
racl whitelist addr ::1

If the netmask is omitted, /32 is assumed for an IPv4 address and /128 is assumed for an IPv6
address.

You should at least whitelist localhost (127.0.0.1/8), and if you have some user clients
connecting to the machine, you should whitelist the addresses they connect from if you don't want
them to get error messages when sending e-mail.

domain This clause selects source machines based on their DNS name, performing a suffix search. For
instance, this will whitelist any machine in the example.net domain:

racl whitelist domain example.net

Suffix search matching means, for example, that gle.com will match google.com. If you want domain
names to match on subdomain boundaries (e.g. gle.com will match mail.gle.com and gle.com but not
google.com) then enable domainexact

The name resolution is made by Sendmail, which hands it to milter-greylist(8). As a result, it is
impossible to use DNS aliases here. On the other hand, this will work even if your DNS resolver is not
thread-safe.

from This is used to select sender e-mail addresses You should not use that feature, because sender e-
mail addresses can be trivially forged.

Please note that the sender e-mail is cleared from spaces and anything leading an equal (=) sign
so that mailing-lists return-address with unique return paths can still match. If you need
unedited sender address, use a rawfrom clause.

Here is an example:

racl whitelist from postmaster@example.com

rawfrom
Same as from but the sender e-mail address is not modified to stip anything. rcpt This is used to
select recipient addresses. Example:

racl greylist rcpt John.Doe@example.net

rcptcount
Followed by an operator and a recipient count, this is used to select the amount of recipients.
Example:

racl blacklist rcptcount >= 25 msg "No more than 25 recipients, please"

helo Followed by a quoted string or a regular expression, this can be used to filter on the HELO
string.

sm_macro
This is used to select a Sendmail macro value. See the section on that topic for more information.

time This is used to specify a time set. It should be followed by a quoted string of crontab(5)-like
time specification. Here is an example that whitelists mail addressed to a single recipient during
office hours (from 8:00 to 16:59 from monday to friday):

racl whitelist time "* 8-16 * * 1-5" rcpt info@example.net

geoip This is used to specify a country, as reported by GeoIP. The country code must be upper case, and
is only available if milter-greylist was built with GeoIP support. Special country code ZZ is used
when the country cannot be determined (this happens for private addresses, for instance). The
geoipdb statement can be used to specify the location of GeoIP database. geoipv6db statement can
be used to specify the location of GeoIPv6 database. geoip2db statement can be used to specify
the location of GeoIP2 (maxminddb) database.

p0f This is used to match against the remote system OS fingerprint genre and detail,obtained from p0f.
It is only available if milter-greylist was built with p0f support. p0f clauses can be used with
a quoted string for case-insensitive substring match, or against regular expressions. The p0fsock
statement can be used to specify the location of the p0f socket.

auth This is used to select a user that succeeded SMTP AUTH. In order to select any user that succeeds
SMTP AUTH, you can use a regular expression matching, like below;

racl whitelist auth /.*/

Using such a clause automatically disable global STARTTLS and SMTP AUTH whitelisting, like if the
noauth keyword would have been used.

tls This is used to select the distinguished name (DN) of a user that succeeded STARTTLS. Using such a
clause automatically disable global STARTTLS and SMTP AUTH whitelisting, like if the noauth
keyword would have been used.

spf This is used to test SPF status. Possible values are pass, softfail, fail, neutral, unknown,
error, none, and self. The first seven values are plain SPF validation status. The self value is
a special test that checks the server's local IP address against the sender's SPF record. If that
test validates, odds are good that the sender SPF record is wide open, and this is hint that SPF
should not be trusted.

In order to use spf self, Postfix users must specify the local address in the configuration file,
using the localaddr option.

Absence of any value after the spf keyword is a synonym for spf pass. This is present for
backward compatibility.

The spf clause is only available if SPF support was compiled in. Using it will disable global SPF
whitelisting, like if the nospf keyword would have been used.

ldapcheck
This is used to query an LDAP directory. See the section on that topic for more information.

urlcheck
This is used to query an external configuration source through an URL. See the section on that
topic for more information.

dnsrbl This is used to select a DNSRBL. See the section on that topic for more information.

nsupdate
This always-matching clause performs a DNS update, see the section on that topic for more
information.

The domain, from, and rcpt clauses may be used with regular expressions. The regular expressions must be
enclosed by slashes (/). No escaping is available to provide a slash inside a regular expression, so just
do not use it. Regular expressions follow the format described in re_format(7). Here is an example:

racl greylist rcpt /@example\.net$/

When regular expressions are not used, from, and rcpt perform a case insensitive substring match with
leading and trailing brackets, spaces and tabs stripped out. domain performs a case insensitive suffix
match. This means, for example, that gle.com will match google.com. If you want domain names to match on
subdomain boundaries (e.g. gle.com will match mail.gle.com and gle.com but not google.com) then enable
domainexact

An ACL entry can also hold various optional parameter used on match: delay, autowhite, flushaddr, nolog,
code, ecode, report, maxpeek, addheader, addfooter, and msg

delay Specify the greylisting delay used before the message can be accepted. This overrides the
greylist global setting, and it only makes sense on an racl greylist entry.

autowhite
Specify the autowhitelisting duration for messages matching this ACL. This overrides the
autowhite global setting, and it only makes sense on an racl greylist entry. Example:

racl greylist rcpt JDoe@example.net delay 15m autowhite 3d
racl greylist rcpt root@example.net delay 1h autowhite 3d

flushaddr
If a message matches the rule, any entry in the greylist or autowhite databases matching the
sender IP is removed. Used with a DNSRBL blacklist ACL, it is useful for freeing the database from
entries set up by a machine which is known to be a spammer. Example:

racl blacklist dnsrbl "known-spammer" flushaddr

nolog Do not generate syslog message if this rule matches. Example:

racl whitelist default nolog

code

ecode

msg These 3 values can be used to choose the SMTP code, extended code and reply message for temporary
failures and rejects. Example:

racl blacklist dnsrbl "spamstomp" msg "IP caught by spamstomp"
racl greylist default code "451" ecode "4.7.1"

The msg strings accepts format string substitution as documented in the FORMAT STRINGS section.
For instance, %A gets substituted by the ACL line number.

None of the last 3 values makes sense for a whitelist entry.

report This value overrides the text displayed in the X-Greylist header, for messages that milter-
greylist(8) lets pass through, either because they are whitelisted, or because they passed
greylisting (see REPORTING). This string can be substituted as documented in the FORMAT STRINGS
section.

maxpeek
This parameter only makes sense in a RCPT-stage ACL. It overrides the global maxpeek setting for
DATA-stage handling of the message. It has no effect if global maxpeek is set to 0.

addheader
This quoted string is a RFC822 header that gets added to the message. Format string substitution
is supported. No check is done for header length standard compliance, so make sure the substituted
string is shorter than 2048 characters. Headers are appended to the bottom, unless an optionnal
comma-separated positive index is specified after the quoted string; in this case the header will
be inserted at this index point from the top. Here is an example:
racl continue addheader "X-Personnal-Header: Hello world!",1

addfooter
Append a footer to the message. Usual escape sequences such as \n can be used to get special
characters. The string is subject to format string expantion as described in the FORMAT STRINGS
section. The footer will not be append if milter-greylist was not able to capture the whole
message, therefore maxpeek must be set approriately.

Entries in the access-list are evaluated sequentially, so order is very important. The first matching
entry is used to decide if a message will be whitelisted or greylisted. A special default clause can be
used in the last ACL entry as a wildcard. Here are a few complete ACL examples:

Example 1:

racl whitelist from friend@toto.com rcpt grandma@example.com
racl whitelist from other.friend@example.net rcpt grandma@example.com
racl greylist rcpt grandma@example.com
racl whitelist default

Example 2:

racl whitelist addr 193.54.0.0/16 domain friendly.com
racl greylist rcpt user1@atmine.com
racl greylist rcpt user2@atmine.com
racl greylist rcpt user3@atmine.com
racl whitelist default

Example 3:

racl whitelist rcpt /@.*otherdomain\.org$/
racl whitelist addr 192.168.42.0/24 rcpt user1@mydomain.org
racl whitelist from friend@example.net rcpt /@.*mydomain\.org$/
racl whitelist rcpt user2@mydomain.org
racl greylist rcpt /@.*mydomain\.org$/
racl whitelist default

DATA-STAGE ACL

ACL using the racl keyword are evaluated at the RCPT stage of the SMTP transaction. It is also possible
to have ACL evaluated at the DATA stage of the SMTP transaction, using the dacl keyword, provided the
message went through RCPT-stage ACL, and possibly greylisting. Note that you cannot use the greylist
action at DATA-stage if the RCPT-stage ACL that matched had a greylist action itself. The following
clauses can be used to work on message content:

dkim DKIM status (if build with DKIM support). Possible values are pass, fail, unknown, error, and
none,

header String or regular expression searched in message headers

body String or regular expression searched in message body

msgsize
Operator followed by a message size (k or M suffix allowed for kilobytes or megabytes). Example:

dacl blacklist msgsize >= 4M msg "No more than 4 MB please"

spamd SpamAssassin score (if build with SpamAssassin support). If used without comparison operator spamd
is true if the score is above threshold. The spamdsock keyword can be used to specify the location
of the spamd socket.

Example 1:

spamdsock unix "/var/spamassassin/spamd.sock"
racl whitelist default
dacl greylist spamd

Example 2:

spamdsock inet "127.0.0.1:783"
racl whitelist default
dacl blacklist spamd > 15 msg "Your message is considered spam."
dacl greylist spamd > 10 delay 2h
dacl greylist spamd > 5 delay 1h

Note that if there are multiple recipient, a rcpt clause at DATA stage evaluates to true if it matches
any of them. If you want to match an exact set of recipients, you can use multiple rcpt clauses along
with a rcptcount clause.

LISTS

       It  is  often useful to group several users or sender IP addresses in a single ACL. This can be done with
       lists. Lists must be first defined and given a name before they can be used in ACL entries.  Here  is  an
       example:

                list "my users" rcpt { user1@example.com user2@example.com }
                list "local" addr { 192.0.2.0/24 10.0.0.0/8 }

                racl whitelist list "local"
                racl greylist list "my users"
                racl whitelist default

BACKWARD COMPATIBILITY

       Previous  versions  of  milter-greylist(8)  used  addr,  domain,  from,  and rcpt lines, without the racl
       keyword.  Access-list management is intended to replace them.  These lines are still accepted by  milter-
       greylist(8),  but  they  are  deprecated.   milter-greylist(8) handles them as access-list entries with a
       single clause. They are added at the head of the access-list so the use of  these  keywords  and  access-
       lists may lead to unspecified behaviour. Do not mix them.

       test mode (using -T) is also deprecated. Access-list semantics do not depend on this flag.

       milter-greylist(8)  also used to only have a RCPT-stage ACL, which was configured through acl statements.
       These have been replaced by racl statements (as opposed to dacl  statements  for  DATA-stage  ACL).   acl
       statements are still accepted for backward compatibility and are a synonym for racl statements.

MX SYNC

       Synchronization  of  the greylist among multiple MX is configured using the peer keyword. List each other
       MX IP addresses using the peer keyword. Here is an example:

         peer 192.0.2.18
         peer 192.0.2.17
         peer 192.0.2.22 timeout 7
         peer 192.0.2.38 timeout 5m

       You can list the local machine in the peer statements, it will be ignored.

       The timeout clause sets a peer communication timeout to have proper retrial in case of slow MX peer.  The
       default value is 3 seconds. The special value of 0 disables the connection retrials.

       By default, milter-greylist will listen on all interfaces using TCP port 5252 or the port number given by
       service  named  mxglsync  if  defined  in /etc/services or other directory service. This behaviour can be
       changed by using the syncaddr keyword. Here are a few examples:

         syncaddr *
         syncaddr * port 7689
         syncaddr 192.0.2.2 port 9785
         syncaddr 2001:db8::1:c3b5:123
         syncaddr 2001:db8::1:c3b5:123 port 1234

       Using '*' as the address means to bind to all local interfaces' addresses.  Note  that  if  you  are  not
       using the default port, all MXs must use the same port number.

       For  outbound  connections  the  system is selecting one of the possible addresses.  If you want to use a
       specific IP you can use:

         syncsrcaddr 123.456.78.9

TEXT DUMP

       milter-greylist(8) uses a text dump of its database to resume  operation  after  a  crash.  The  dump  is
       performed  at  regular  time  interval,  but  as  it  is a heavy operation, you might want to configure a
       particular time interval, using the dumpfreq option.

       If the dumpfreq value is too small, it will kill performance. If it is too high, you will loose a  bigger
       part of the database on a crash.

       Set  dumpfreq to 0 to get a dump on each change (kills performance), Set it to -1 to never dump to a file
       (unsafe as you lose the whole greylist on each crash), or give a time value for the delay between  dumps.
       The time is given in seconds, except if a unit is given: m for minutes, h for hours, and d for days.

       You  may  further  improve  the  performance  of  the  dump  operation at the expense of humanly readable
       timestamp which by default appears as a comment at the end of each line in the dumpfile. You may  disable
       generation  of this comment by specifying dump_no_time_translation option in the configuration file. This
       is specifically recommended if your dumpfile grows to 100's of megabytes - it can reduce the time  needed
       for the dump operation by the order of magnitude!

REPORTING

       By  default,  milter-greylist(8) will add a X-Greylist header to any message it handles. The header shows
       what happened to the message: delayed or not delayed, and why. The  following  options  can  be  used  in
       greylist.conf to alter this behavior:

       report none
              Never add a X-Greylist header.

       report delays
              Only add a header if the message was delayed.

       report nodelays
              Add a header if the message was not delayed. The header explains why the message was not delayed.

       report all
              Always add a header. This is the default.

SENDER CALLBACK SYSTEMS

       Sender  callback  systems are another anti-spam measure that attempts to send a DSN to the sender address
       before accepting a message. If that fails, then the sender address is wrong and the message is  rejected.
       Such systems usually stop their callback check at the RCPT stage of the SMTP transaction.

       Greylisting  temporarily rejects at the RCPT stage, so sender callback and greylisting love to fight each
       other.  milter-greylist(8) proposes a workaround to that  problem  with  the  delayedreject  option.  For
       messages  coming  from  <>  (that  is, for DSN), it will cause the temporary reject to happen at the DATA
       stage of the SMTP transaction instead of the RCPT stage. That  way,  milter-greylist(8)  will  cope  much
       better with sender callback systems.

       This  has  a  minor  drawback  (and this is why it is not enabled by default): for a multi recipient DSN,
       whitelisted recipient will not be honoured: the message will be delayed for everyone.

SENDMAIL MACROS

       Any sendmail macro can be used as a clause in the access list. You need to define a (macro,  value)  pair
       using  the  sm_macro keyword before using it.  Here is an example that uses the {client_resolve} macro to
       apply a larger greylisting delay to hosts that have a bogus reverse DNS:

                sm_macro "maybe_forged" "{client_resolve}" "FORGED"

                racl greylist sm_macro "maybe_forged" delay 1h
                racl greylist default delay 15m

       A regular expression can be used as the macro value.  It must be  surrounded  with  slashes  and  not  by
       quotes.  The special value unset can also be used to match an unset macro:

                sm_macro "not_foo" "{foo}" unset

       Note  that any Sendmail macro that is not exported using the Milter.macros.envrcpt setting of sendmail.cf
       will be seen as unset from milter-greylist.

DNSRBL

       DNS Reverse Black List can be used to toggle an ACL. They must be defined and named before  they  can  be
       used. Here is an example which uses a bigger greylisting delay for hosts caught in the SORBS dynamic pool
       DNRSBL (this will include DSL and cable customers pools, which are well known to be massively infected by
       spamwares):

                dnsrbl "SORBS DUN" dnsbl.sorbs.net 127.0.0.10/32

                racl greylist dnsrbl "SORBS DUN" delay 1h
                racl greylist default delay 15m

       The  definition  of a DNSRBL starts by the dnsrbl keyword, followed by the quoted name of the DNSRBL, the
       DNS domain on which addresses should be looked up, and the answer we should consider as a positive hit.

       DNSRBL support is only available if enabled through the --enable-dnsrbl config  flag.  Please  make  sure
       milter-greylist(8) is linked against a thread-safe DNS resolver, otherwise it shall crash.

DNS updates

       ACL are able to trigger a DNS update, which can be used to feed a DNSRBL.  That functionnality is enabled
       at build time if the DNS resolver has DNS update support.

       Configuration  is  done  with  the nsupdate statement, which may be used several times, and the optionnal
       tsig statement, if you want ot use authenticated DNS update. Here is an example syntax:

                tsig "dns-update" "hmac-md5" "1B2M2Y8AsgTpgAmY7PhCfg=="
                nsupdate "bl.example.net" { rname "%j.bl.example.net" rvalue "127.0.0.2" tsig "dns-update" }

       The options for nsupdate are:

       rname  Created record name, which uses format strings.

       rvalue Created record value, which uses format strings.

       servers
              Quoted comma-separated list of DNS server the update should be sent to.  Default  is  to  use  the
              system confifugration, usualy from /etc/resolv.conf

       ttl    TTL of created DNS record. Default is 0 seconds.

       class  Created record class, as numeric value. Default is 1, for IN class.

       type   Created record type, as numeric value. Default is 1, for A type.

       tsig   The  name  of  a  tsig  configuration,  which  must  have  been  supplied  before. If unspecified,
              unauthenticated DNS updates are performed.

       Once configured, DNS updates can be used in any ACL:

                racl blacklist rcpt spamtrap@example.net nsupdate "bl.example.net"

PROPERTIES

Properties are variables that can be set, evaluated and printed in ACL. A property may be dropped once
the current recipient is processed, or it can be retained until the message is processed. They can be
created through the following always-matching ACL clauses:

set $name="value"
This sets a property that will be retained for all next recipients. Right hand side of the clause
may be a quoted string (which will be substituted using format strings, as described in the FORMAT
STRINGS section), a number, or another property name (which will be substituted by the property
value).

rset $name="value"
Same as set clause, except that the property will be droped once the current user will have been
processed.

urlcheck
These clause will cause properties to be fetched from an external web service. See the URL checks
section below for details.

ldapcheck
These clause will cause properties to be fetched from a LDAP directory See the LDAP CHECKS section
below for details.

Properties can be used as left-hand side part of ACL clauses:

racl blacklist $name "badvalue"
racl blacklist $name /badregex/

If used left-hand side and prefixed by a star, the property will be evaluated as a glob(7) pattern, In
the example below, if sender DNS domain is test.example.net and $domain is *.example.net, we get a match.

racl blacklist *$domain "%f"

They are also available as right-hand side of many ACL clauses:

racl continue set $badword="spam"
racl blacklist body $badword

Values of properties can be obtained in any quoted string that is subject to format string expantion:

racl continue set $webmaster="webmaster@example.net"
racl blacklist domain evil.net msg "blacklisted, ask $P{webmaster} why"

When the property value is a number, it can be increased or decreased using this syntax:

racl continue set $score+=5
racl continue set $score-=5

Here again, right hand side may be a quoted string, a number or another property. For the quoted string
and property cases, a conversion is first made to an integer, using 0 as a value on failure. Note that no
arithmetic evaluation occurs. For instance, the quoted string "1 + 1" will be evaluated as 0.

The log ACL clause can be helpful when one need to figure what happens to property values during the ACL
flow. See the CUSTOM REPORT section for more details.

URL checks

milter-greylist(8) is able to query external sources of information through various URL, if it was built
with --with-libcurl. Here is an example:

urlcheck "glusr" "http://www.example.net/mgl-config?rcpt=%r" 5

racl greylist urlcheck "glusr" delay 15m
racl whitelist default

The trailing 5 at the end of the urlcheck definition is the maximum number of simultaneous connections we
want to launch on this URL. For each message, the URL will be queried, with % format tags being
substituted. For instance, %r is substituted by the recipient. See the FORMAT STRINGS section for the
complete list of substitutions.

milter-greylist(8) expects an answer containing a list of \n terminated lines, with key: value pairs. The
most basic answer to get a match is:

milterGreylistStatus: Ok

TRUE can be used as an alias for Ok here.

The answer can be more complex, with keys that will overload the ACL settings:

milterGreylistDelay
The greylisting delay to use (time unit suffix allowed).

milterGreylistAutowhite
The autowhite delay to use (time unit suffix allowed).

milterGreylistFlushAddr
The value is ignored. If this key is present, then the IP address for the sender machine will be
flushed from greylist and autowhite databases.

milterGreylistCode
The SMTP code to return (e.g.: 551).

milterGreylistECode
The SMTP extended code to return (e.g.: 5.7.1)

milterGreylistMsg
The string to return with SMTP codes.

milterGreylistReport
The string to display in the X-Greylist header.

milterGreylistIgnore
This line will be ignored, without warnings in the logs.

milterGreylistAction
This feature is nifty but use it with caution, as it makes the access list a bit difficult to
understand. By specifying the values greylist, whitelist, or blacklist, it is possible to overload
the ACL action itself.

The ACL will match if any of the above key is returned: milterGreylistStatus is not mandatory.

Optional keywords can be appended to a urlcheck definition:

postmsg
On DATA-stage ACL, This causes the message to be sent (up to maxpeek bytes) in a POST request.
Here is an example:

urlcheck "extfilter" "http://www.example.net/f.cgi" 5 postmsg

dacl blacklist urlcheck "extfilter"
dacl whitelist default

getprop
Gather the properties returned by the URL and reuse them in the ACL. The gathered properties can
be accessed in the current and following ACL by prefixing them by a dollar ($).

clear This causes gathered properties to be cleared on each new recipient. This avoids properties for
several recipients to mix.

fork Tells milter-greylist(8) to fork a separate instance of itself for performing the queries. Use it
if you encounter thread-safety problems. fork is not compatible with postmsg.

domatch
Cause the ldapcheck clause to be evaluated in ACL. Default behavior is to ignore the result and
just fecth properties, except if the LDAP directory is unreachecable, in which case a temporary
failure occurs. The fixldapcheck gloabal settings may also be used to globaly cause all ldapcheck
and urlcheck clauses to match.

Here is an example that will use various DNSRBL depending on a per-recipient setting stored in the dnsrbl
attribute of a LDAP directory.

dnsrbl "RBL2" "rbl.example.net" "127.0.0.2"
dnsrbl "RBL3" "rbl.example.net" "127.0.0.3"
dnsrbl "RBL4" "rbl.example.net" "127.0.0.4"
urlcheck "userconf" "ldap://localhost/dc=example,dc=net?milterGreylistStatus,dnsrbl?one?mail=%r"
5 getprop clear

racl blacklist urlcheck "userconf" $dnsrbl "RBL2" dnsrbl "RBL2"
racl blacklist $dnsrbl "RBL3" dnsrbl "RBL3"
racl blacklist $dnsrbl "RBL4" dnsrbl "RBL4"

Note that when matching gathered properties, format strings and regex can be used.

LDAP CHECKS

       If  milter-greylist  was  built  with  --with-openldap,  then  you  can  also  use  ldapcheck for pulling
       information from an LDAP directory. This works exactly like urlcheck, except that properties  are  always
       collected: The getprop option is implicit.

       A list of LDAP URL to use can be specified with the ldapconf keyword. The network timeout is optional.

                ldapconf "ldap://localhost ldaps://ldap.example.net" timeout 2s

       When ldaps:// is used, the system's ldap.conf file is used to locate x509 certificates.

       When  defining  LDAP  queries with the ldapcheck statement, note that the scheme and host part of the URL
       are ignored.  Servers listed in ldapconf are used instead.

RATE LIMIT

       The ratelimit keyword specifies a ratelimit configuration to be used in access lists. It must be followed
       by the rate limit configuration name, what is being accounted (i.e.: session for SMTP sessions, rcpt  for
       recipients, data for bytes in body and headers), the actual limit, and the sampling period. Example:

                ratelimit "internalclients" rcpt 10 / 1m

                racl blacklist addr 192.0.2.0/24 ratelimit "internalclients" \      msg "you speak too much"

       The  ratelimit  keyword can also have an option key statement, which determine the set of key for message
       accounting. The default is %i for per IP address accounting (see the  FORMAT  STRINGS  sections  for  the
       possible  syntax of this field). Here is an example that configures a rate limit of 100 messages per hour
       for each individual recipient-IP set.

                ratelimit "internalclients" rcpt 100 / 1h key "%r%i"

                racl blacklist addr 192.0.2.0/24 ratelimit "internalclients" \      msg "you speak too much"

CUSTOM REPORTS

       The stat keyword can be used to specify a custom report  for  milter-greylist  activity.   It  should  be
       supplied with an output (either file or external command) and a format string. Here is an example:

                stat ">>/var/log/milter-greylist.log" "%T{%T},%i,%f,%r,%A\n"

       If  the  output  starts  by >> or > then it is a file. Use >> to append to an existing file, and use > to
       overwrite it. If the output starts by a | then the output is a shell command, like in the example below:

                stat "|logger -p local7.info" "%T{%T},%i,%f,%r,%A\n"

       The format string gets substituted as URL checks format string: %r gets substituted by the recipient,  %f
       by the sender, and so on. See the FORMAT STRINGS section for a complete list of available substitutions.

       There is also an always-matching log ACL clause that can be used to send a formated string to syslog with
       LOG_INFO level.  Here is an example:

              racl continue rcpt /@example\.com$/ log "I was here"

COMMAND-LINE FLAG EQUIVALENTS

Most milter-greylist(8) command-line options have equivalent options that can be set in the configuration
file. Note that if a command line option is supplied, it will always override the configuration file.

If a command-line equivalent keyword is used more than once, the last keyword will override the previous
ones.

verbose
Enable debug output. This is equivalent to the -v flag.

quiet Do not tell clients how much time remains before their e-mail will be accepted. This is equivalent
to the -q flag.

nodetach
Do not fork and go into the background. This is equivalent to the -D flag.

noauth Greylist clients regardless if they succeeded SMTP AUTH or STARTTLS. Equivalent to the -A flag.

noaccessdb
Normally milter-greylist(8) will whitelist a message if sendmail(8) defines a ${greylist} macro
set to WHITE. This enables complex whitelisting rules based on the Sendmail access DB. This option
inhibits this behavior.

nospf Greylist clients regardless if they are SPF-compliant. Equivalent to the -S flag.

testmode
Enable test mode. Equivalent to the -T flag. This option is deprecated.

greylist
The argument sets how much time milter-greylist(8) will want the client to wait between the first
attempt and the time the message is accepted. The time is given in seconds, except if a unit is
given: m for minutes, h for hours, and d for days. The greylist keyword is equivalent to the -w
option. Here is an example that sets the delay to 45 minutes:

greylist 45m

autowhite
This sets the auto-whitelisting duration, equivalent to the -a command-line option. As for the
greylist keyword, units can be supplied. Here is an example for a 3 day long auto-whitelisting:

autowhite 3d

pidfile
This causes milter-greylist(8) to write its PID into the file given as argument, like the -P
command line argument does. The path to the file must be absolute and it must be enclosed in
quotes. Here is an example:

pidfile "/var/run/greylist.pid"

dumpfile
This chooses the location of the greylist dump file, like the -d command line option does. The
path must be absolute and enclosed in quotes. It can optionally be followed by an octal
permission mode. Example:

dumpfile "/var/milter-greylist/greylist.db" 640

subnetmatch
This is equivalent to the -L command line option. It takes a slash followed by a CIDR mask as
argument, and it commands the subnet matching feature. Example, for a class C wide matching:

subnetmatch /24

subnetmatch6
This is equivalent to the -M command line option. It takes a slash followed by a prefixlen as
argument, and it commands the subnet matching feature. Example, for a subnet wide matching:

subnetmatch6 /64

socket Like the -p command line option, this keyword is used to specify the socket used to communicate
with sendmail(8). It must be enclosed in quotes and can optionally be followed by an octal
permission mode (valid values are 666, 660 or 600, other values cause an error):

socket "/var/milter-greylist/milter-greylist.sock" 660

user This keyword should be followed by a quoted user login and optionally a colon followed by a
groupname. Like the -u option, this is used to run milter-greylist(8) as a non root user. Here
is an example:

user "smmsp"

MISCELLANEOUS

These options have no command line equivalent:

logfac Sets the syslog facility for messages. Can be set to any of the standard facilities: kern, user,
mail, daemon, auth, syslog, lpr, news, uucp, cron, authpriv, ftp, local0, local1, local2, local3,
local4, local5, local6, local7. Can also be set to none to disable syslog output completely.

timeout
is used to control how long greylist tuples are retained in the database. Value is in seconds,
except if a suffix is given (m for minutes, h for hours, d for days). Default is 5 days.

extendedregex
Use extended regular expressions instead of basic regular expressions.

unbracket
Attempt to resolve sender address when the MTA handed it as bracketed IP address (e.g.:
[192.0.2.18] ). Default is to leave it as is.

maxpeek
Limit (in bytes) how much of messages are examined for header and body searches.

lazyaw Make auto-whitelist look at just the IP instead of the (sender IP, sender e-mail address,
recipient e-mail address) tuple.

domainexact
match on subdomain boundaries instead of the default suffix matching. E.g. if domainexact is not
enabled (the default) then gle.com will match google.com in addition to gle.com. If domainexact is
enabled then, domain names will match on subdomain boundaries (e.g. gle.com will match
mail.gle.com and gle.com but not google.com)

drac db
Tell where the DRAC DB file is. This is only available if DRAC support was compiled in. Here is an
example:

drac db "/usr/local/etc/drac.db"

nodrac Disable DRAC.

logexpired
This option causes greylist entries that expire to be logged via syslog. This allows you to
easily collect the IP addresses and sender names and use them for blacklisting, SPAM scoring, etc.
Normally, expiration's are only logged if the debug option is set, but that generates a lot of
extra messages.

localaddr
This keyword can be used to manually define the local MTA's IP address for such uses as spf self
and p0f in absence of the milter-API {if_addr} macro support in your MTA (Postfix, Sun/Oracle
CommSuite Messaging Server). This is not so useful when using Sendmail, since it serves the macro
and the local address can be detected automatically.

The configuration file is reloaded automatically once it is modified when new e-mail arrives. Most
configuration keywords will take effect immediately, except the following, which will only take effect
after a restart of milter-greylist(8): nodetach, pidfile, socket, and user.

The dumpfreq option can be changed dynamically, but the change will only take effect after the next dump.

multiracl
By default, once a RCPT-stage ACL whitelists a recipient, next recipient gets automatically
whitelisted. This historical behavior can be considered a bug, and this option disables it.

FORMAT STRINGS

Various statements in the configuration file accept format strings, where the following % prefixed tokens
are substituted. Here is the complete list of available substitutions (Note that some substitutions are
not relevant in any context).

%r the message recipient e-mail address. This is not substituted for DATA stage ACL since there can
be multiple recipients for the message.

%f the message sender e-mail address

%i the sender machine IP address

%j the reversed sender machine IP address. For instance, 192.0.2.12 becomes 12.2.0.192.

%I the sender machine IP address masked by a CIDR. Example: %I{/24}

%d the sender machine DNS address

%h the SMTP transaction HELO string

%mr the mailbox part of %r (before the @ sign). This is not substituted for DATA stage ACL since there
can be multiple recipients for the message.

%sr the site part of %r (after the @ sign). This is not substituted for DATA stage ACL since there can
be multiple recipients for the message.

%mf the mailbox part of %f (before the @ sign)

%sf the site part of %f (after the @ sign)

%md the machine part of %d (before the first . sign)

%sd the site part of %d (after the first . sign)

%Xc the SMTP code returned

%Xe the SMTP extended code returned

%Xm the SMTP message returned

%Xh the message displayed in the X-Greylist header

%D Comma-separated list of DNSRBL for which the sender host matched

%M a sendmail macro value. Examples: %Mj or %M{if_addr}

%g a regex back reference. For instance, %g{\2} is substituted by the string matching the second
parenthesis group in all ACL regex clauses

%T a brace-enclosed strftime(3) format string that will be substituted by the system time. Example:
%T{%Y%m%d:%H%M%S}

%v milter-greylist's version

%G Offset to GMT (e.g.: -0100)

%C Sender IP country code, as reported by GeoIP. This is only available if milter-greylist was built
with GeoIP support

%Fx p0f OS fingerprint genre and detail. This is only available if milter-greylist was built with p0f
support.

%V Shortcut to "milter-greylist-%v (%Mj [%M{if_addr}]); %T{%a, %d %b %Y %T} %G (%T{%Z})"

%S the action performed: accept, tempfail, or reject.

%A the line number of the ACL that caused the action.

%a the id string of the ACL that caused the action. If no id was given, the line number is used
instead.

%cA the line number of the ACL being evaluated, whether it matches or not.

%ca the id string of the ACL being avaluated, whether it matches or not. If no id was given, the line
number is used instead.

%Et total elapsed time in seconds before a greylisted message has been accepted

%Eh hours elapsed

%Em minutes elapsed (modulo one hour)

%Es seconds elapsed (modulo one minute)

%E shortcut to %Eh:%Em:Es

%Rt total remaining time in seconds before a greylisted message will be accepted

%Rh hours remaining

%Rm minutes remaining (modulo one hour)

%Rs seconds remaining (modulo one minute)

%R shortcut to %Rh:%Rm:Rs

%Hs SpamAssassin score (if build with SpamAssassin support)

%pn Name of last LDAP or CURL gathered property that matched an ACL.

%pv Value of last LDAP or CURL gathered property that matched an ACL.

%pr Recipient that caused storage of the last matching LDAP or CURL gathered property. %P a LDAP or
CURL gathered propery. Example: %P{mail} Note that this copes very badly with multivalued
properties.

%Qd DKIM query result (pass, fail, etc.), if built with DKIM support.

%Qs SPF query result (pass, (soft)fail, etc.), if built with SPF support.

%QA Authentication results summary, suitable for Authentication-Results header. Will included
formatted query results from DKIM and SPF if checked.

%QS SPF result, suitable for Received-SPF header. Available when compiled with libspf2.

%% a single % character

AUTHORS

       Emmanuel Dreyfus <manu@netbsd.org>

       milter-greylist  received many contributions from (in alphabetical order): Adrian Dabrowski, Aida Shinra,
       Adam Katz, Alexander Lobodzinski, Alexandre Cherif, Alexey Popov, Andrew McGill, Attila Bruncsak,  Benoit
       Branciard,  Bernhard  Schneider,  Bob  Smith, Constantine A. Murenin, Chris Bennett, Christian Pelissier,
       Cyril Guibourg, Dan Hollis, David Binderman, Denis  Solovyov,  Elrond,  Enrico  Scholz,  Eugene  Crosser,
       Fabien  Tassin,  Fredrik  Pettai,  Gary  Aitken,  Georg Horn, Gert Doering, Greg Troxel, Guido Kerkewitz,
       Hajimu Umemoto, Hideki ONO, Ivan F. Martinez, Jacques Beigbeder, Jean  Benoit,  Jean-Jacques  Puig,  Jeff
       Rife,  Jim  Klimov,  Jobst Schmalenbach, Joe Pruett, Joel Bertrand, Johann E. Klasek, Johann Klasek, John
       Thiltges, John Wood, Jorgen Lundman, Kazuyuki Yoshida, Klas Heggemann, Kouhei Sutou,  Laurence  Moindrot,
       Lev  Walkin,  Manuel  Badzong,  Markus  Wennrich,  Mart Pirita, Martin Paul, Matt Kettler, Mattheu Herrb,
       Matthias Scheler, Matthieu Herrb, Michael Fromme,  Moritz  Both,  Nerijus  Baliunas,  Ole  Hansen,  Pavel
       Cahyna,  Pascal  Lalonde,  Per  Holm,  Petar  Bogdanovic, Petr Kristof, Piotr Wadas, R P Herrold, Ralf S.
       Engelschall, Ranko Zivojnovic, Remy Card, Rick Adams, Rogier Maas, Romain Kang, Rudy Eschauzier, Stephane
       Lentz, Steven Hiscocks, Thomas Scheunemann, Tim Mooney, Vincent Dufresne, Wolfgang Solfrank, and Yaroslav
       Boychuk.

       Thanks to Helmut Messerer and Thomas Pfau for their feedback on the first releases of this software.