dccm(8) Distributed Checksum Clearinghouse dccm(8)
dccm -- Distributed Checksum Clearinghouse Milter Interface
dccm [-VdbxANQ] [-G on | off | noIP | IPmask/xx] [-h homedir] [-I user]
[-p protocol:filename | protocol:port@host] [-m map]
[-w whiteclnt] [-U userdirs] [-a IGNORE | REJECT | DISCARD]
[-t type,[log-thold,]rej-thold] [-g [not-]type] [-S header]
[-l logdir] [-R rundir] [-r rejection-msg] [-j maxjobs]
[-B dnsbl-option] [-X xfltr-option] [-L ltype,facility.level]
Dccm is a daemon built with the sendmail milter interface intended to
connect sendmail to DCC servers. When built with the milter filter
machinery and configured to talk to dccm in the sendmail.cf file, send-
mail passes all email to dccm which in turn reports related checksums to
the nearest DCC server. Dccm then adds an X-DCC SMTP header line to the
message. Sendmail is told to reject the message if it is unsolicited
bulk mail.
dccm sends reports of checksums related to mail received by DCC clients
and queries about the total number of reports of particular checksums. A
DCC server receives no mail, address, headers, or other information, but
only cryptographically secure checksums of such information. A DCC
server cannot determine the text or other information that corresponds to
the checksums it receives. Its only acts as a clearinghouse of counts
for checksums computed by clients. For complete privacy as far as the
DCC is concerned, the checksums of purely internal mail or other mail
that is known to not be unsolicited bulk can be listed in a whitelist to
not be reported to the DCC server.
Since the checksums of messages that are whitelisted locally by the -w
whiteclnt file are not reported to the DCC server, dccm knows nothing
about the total recipient counts for their checksums and so cannot add
X-DCC header lines to such messages. Sendmail does not tell dccm about
messages that are not received by sendmail via SMTP, including messages
submitted locally and received via UUCP, and so they also do not receive
X-DCC header lines.
The list of servers that dccm contacts is in a memory mapped file shared
by local DCC clients. The file is maintained with cdcc(8). Put parame-
ters into the dcc_conf file and start the daemon with the start-dccm
script.
When sendmail is not used, then dccm is not useful. dccproc(8) or
dccifd(8) can often be used instead.
OPTIONS
The following options are available:
-V displays the version of the DCC Milter interface.
-d enables debugging output from the DCC client library. Additional -d
options increase the number of messages. A single -d
aborted SMTP transactions including those from some "dictionary
attacks."
-b causes the daemon to not detach itself from the controlling tty and
put itself into the background.
-x causes the daemon to try "extra hard" to contact a DCC server.
Since it is usually more important to deliver mail than to report
its checksums, dccm normally does not delay too long while trying to
contact a DCC server. It will not try again for several seconds
after a failure. With -x, unresponsive DCC servers cause mail to be
temporarily rejected with 4.7.1 451 DCC failure
-A adds to existing X-DCC headers in the message instead of replacing
existing headers of the brand of the current server.
-N neither adds, deletes, nor replaces existing X-DCC headers in the
message. Each message is logged, rejected, and otherwise handled
the same.
-Q only queries the DCC server about the checksums of messages instead
of reporting and querying. This is useful when dccm is used to fil-
ter mail that has already been reported to a DCC server by another
DCC client. No single mail message should be reported to a DCC
server more than once per recipient, because each report will
increase the apparent "bulkness" of the message.
It is better to use MXDCC lines in the global whiteclnt file for
your MX servers
-G on | off | noIP | IPmask/xx
controls greylisting. At least one working greylist server must be
listed in the map file in the DCC home directory. If more than one
is named, they must "flood" or change checksums and they must use
the same -G parameters. See dccd(8). Usually all dccm or dccifd
DCC client processes use the same -G parameters.
IPmask/xx and noIP remove part or all of the IP address from the
greylist triple. The CIDR block size, xx, must be between 1 and
128. 96 is added to block sizes smaller than 33 to make them appro-
priate for the IPv6 addresses used by the DCC. IPmask/96 differs
from noIP because the former retains the IPv4 to IPv6 mapping pre-
fix.
-h homedir
overrides the default DCC home directory, which is often /var/lib/dcc.
-I user
specifies the UID and GID of the process.
-p protocol:filename | protocol:port@host
specifies the protocol and address by which sendmail will contact
dccm. The default is a UNIX domain socket in the "run" directory,
often /var/run/dcc/dccm. (See also -R) This protocol and address
must match the value in sendmail.cf. This mechanism can be used to
connect dccm on one computer to sendmail on another computer when a
port and host name or IP address are used.
-m map
specifies a name or path of the memory mapped parameter file instead
of the default map file in the DCC home directory. It should be
created with the cdcc(8) command.
-w whiteclnt
specifies an optional file containing SMTP client IP addresses, SMTP
envelope values, and header values of mail that is spam or is not
spam and does not need a X-DCC header, and whose checksums should
not be reported to the DCC server.
If the pathname whiteclnt is not absolute, it is relative to the DCC
home directory. The format of the dccm whiteclnt file is the same
as the whitelist files used by dbclean(8) and the whiteclnt file
used by dccproc(8). See dcc(8) for a description of DCC white and
blacklists. Because the contents of the whiteclnt file are used
frequently, a companion file is automatically created and main-
tained. It has the same pathname but with an added suffix of .dccw
and contains a memory mapped hash table of the main file.
A white-list entry ("OK") or two or more semi-white-listings ("OK2")
for the message's checksums prevents all of the message's checksums
from being reported to the DCC server and the addition of a X-DCC
header line by dccm (except for env_To checksums). A white-listing
entry for a checksum also prevents rejecting or discarding the mes-
sage based on DCC recipient counts as specified by -a and -t. Oth-
erwise, one or more checksums with blacklisting entries ("MANY")
cause all of the message's checksums to be reported to the server
with an addressee count of "MANY".
White-list env_To values are handy for white-listing or exempting
destination addresses such as Postmaster from filtering and for mak-
ing "spam traps" of addresses that should never receive mail. First
an entry for the official envelope Rcpt To value is sought. If that
is not found, dccm looks for an entry for the sendmail "user"
string. Mail sent to blacklisted addresses or with other black-
listed values such as From or env_From values is reported to the DCC
server as spam or with target counts of millions.
If the message has a single recipient, an env_To whiteclnt entry of
"OK" for the checksum of its recipient address acts like any other
whiteclnt entry of "OK." When the SMTP message has more than one
recipient, the effects can be complicated. When a message has sev-
eral recipients with some but not all listed in the whiteclnt file,
dccm tries comply with the wishes of the users who want filtering as
well as those who don't by silently not delivering the message to
those who want filtering (i.e. are not white-listed) and delivering
the message to don't want filtering.
Consider an option dcc-off line in per-user whiteclnt files to turn
off DCC filtering for individual mailboxes.
-U userdirs
enables per-user whiteclnt and log files. Each target of a message
can have a directory of log files named usedirs/${dcc_userdir}/log
where ${dcc_userdir} is the sendmail.cf macro described below. If
${dcc_userdir} is not set, userdirs/${rcpt_mailer}/${rcpt_addr}/log
is used. If it is not absolute, userdirs is relative to the DCC
home directory. The sub-directory prefixes for -l logdir are not
honored. The directory containing the log files must be named log
and it must be writable by the dccm process. Each log directory
must exist or logging for the corresponding is silently disabled.
The files created in the log directory are owned by the UID of the
dccm process, but they have group and other read and write permis-
sions copied from the corresponding log directory. To ensure the
privacy of mail, it may be good to make the directories readable
only by owner and group, and to use a cron script that changes the
owner of each file to match the grandparent addr directory.
There can also be userdirs/${dcc_userdir}/whiteclnt, or if
${dcc_userdir} is not set, userdirs/${rcpt_mailer}/${rcpt_addr} per-
user whitelist files. The name of each file must be whiteclnt.
Every checksum including the env_to and sendmail "user" values are
looked for first in the userdirs/mailer/addr/whiteclnt and list then
in the global -w whiteclnt list. A missing per-address whiteclnt
file is the same as an empty file. Relative paths for whitelists
included in per-address whiteclnt are resolved in the DCC home
directory. The whiteclnt files and the addr directories containing
them must be writable by the dccm process.
The most likely value of mailer is local. Appropriate values for
both mailer and addr can be seen by examining env_To lines in -l
logdir files.
-a IGNORE | REJECT | DISCARD
specifies the action taken when DCC server counts or -t thresholds
say that a message is unsolicited bulk. IGNORE causes the message
to be unaffected except for adding the X-DCC header line to the mes-
sage. This turns off DCC filtering.
Spam can also be REJECTed, or accepted and silently DISCARDed with-
out being delivered to local mailboxes. The default is REJECT.
Mail forwarded via IP addresses marked MX or MXDCC in the main
whiteclnt file is treated as if -a DISCARD were specified. This
prevents "bouncing" spam.
With an action of REJECT or DISCARD, spam sent to both white-listed
targets and non-white-listed targets is delivered to white-listed
targets and if possible, silently discarded for non-white-listed
targets. This is not possible if there are too many non-white-
listed targets to be saved in a buffer of about 500 bytes.
Determinations that mail is or is not spam from sendmail via
${dcc_isspam} or ${dcc_notspam} macros override -a. The effects of
the -w whiteclnt are also not affected by -a.
-t type,[log-thold,]rej-thold
sets logging and "spam" thresholds for checksum type. The checksum
types are IP, env_From, From, Message-ID, substitute, Received,
Body, Fuz1, and Fuz2. The string ALL sets thresholds for all types,
but is unlikely to be useful except for setting logging thresholds.
The string CMN specifies the commonly used checksums Body, Fuz1, and
Fuz2. Rej-thold and log-thold must be numbers, the string NEVER, or
the string MANY indicating millions of targets. Counts from the DCC
server as large as the threshold for any single type are taken as
sufficient evidence that the message should be logged or rejected.
Log-thold is the threshold at which messages are logged. It can be
handy to log messages at a lower threshold to find solicited bulk
mail sources such as mailing lists. If no logging threshold is set,
only rejected mail and messages with complicated combinations of
white and blacklisting are logged. Messages that reach at least one
of their rejection thresholds are logged regardless of logging
thresholds.
Rej-thold is the threshold at which messages are considered "bulk,"
and so should be rejected or discard if not white-listed. Use -a
REJECT or -a Discard to reject or discard bulk mail that is not
white-listed. Use -a IGNORE to only add X-DCC headers with the
"bulk" or "bulk rep" string.
DCC reputation thresholds in the commercial version of the DCC are
controlled by thresholds on checksum types rep and rep-total. Mes-
sages from an IP address that the DCC database says has sent more
than rep-total log-thold messages are logged. A DCC reputation is
computed for messages received from IP addresses that have sent more
than rep-total rej-thold messages. The DCC reputation of an IP
address is the percentage of its messages that have been detected as
bulk, or having at least 10 recipients. The defaults are equivalent
to -t rep,never and -t rep-total,never,10. Bad DCC reputations do
not cause the rejection of mail unless enabled by a option
DCC-reps-on line in the -w whiteclnt or the whiteclnt file in the
user's -U userdirs directory.
The checksums of locally white-listed messages are not checked with
the DCC server and so only the number of targets of the current copy
of a white-listed message are compared against the thresholds.
The default is -t ALL,NEVER, so that nothing is discarded or logged.
A common choice is -t CMN,25,50 to reject or discard mail with com-
mon bodies except as overridden by the whitelist of the DCC server,
the sendmail ${dcc_isspam} and ${dcc_notspam} macros, and -g, and
-w.
-g [not-]type
indicates that white-listed, OK or OK2, counts from the DCC server
for a type of checksum are to be believed. They should be ignored
if prefixed with not-. Type is one of the same set of strings as
for -t. Only IP, env_From, and From are likely choices. By default
all three are honored, and hence the need for not-.
-S hdr
adds to the list of substitute or locally chosen headers that are
checked with the -w whiteclnt file and sent to the DCC server. The
checksum of the last header of type hdr found in the message is
checked. Hdr can be HELO to specify the SMTP envelope HELO value.
Hdr can also be mail_host to specify the sendmail "resolved" host
name from the Mail_from value in the SMTP envelope. As many as 6
different substitute headers can be specified, but only the checksum
of the first of the six will be sent to the DCC server.
-l logdir
specifies a directory in which files containing copies of messages
processed by dccm are kept. Each file is given 0600 permissions
unless logdir is cannot be accessed by 'other', in which case the
files are group-readable if the directory is. They can also be
copied to per-user directories specified with -U. Information about
other recipients of a message is deleted from the per-user copies.
If logdir starts with D?, log files are put into subdirectories of
the form logdir/JJJ where JJJ is the current julian day. H?logdir
puts logs files into subdirectories of the form logdir/JJJ/HH where
HH is the current hour. M?logdir puts log files into subdirectories
of the form logdir/JJJ/HH/MM where MM is the current minute. See
the FILES section below concerning the contents of the files.
The directory is relative to the DCC home directory if it is not
absolute
-R rundir
specifies the "run" directory where the UNIX domain socket and file
containing the daemon's process ID are stored. The default value is
often /var/run/dcc.
-r rejection-msg
specifies the rejection message for unsolicited bulk mail or for
mail temporarily blocked by greylisting when -G is specified. The
first -r rejection-msg replaces the default bulk mail rejection mes-
sage, "5.7.1 550 mail %s from %s rejected by DCC". The second
replaces "4.2.1 452 mail %s from %s temporary greylist embargoed".
The third -r rejection-msg replaces the default SMTP rejection mes-
sage "5.7.1 550 %s bad reputation; see http://commercial-dcc.rhyo-
lite.com/cgi-bin/reps.cgi?tgt=%s" for mail with bad DCC reputations.
If rejection-msg is the zero-length string, the -r setting is
counted but the corresponding message is not changed.
There can be up to two "%s" strings. The first %s is replaced by
the sendmail queue ID and the second is replaced by the IP address
of the SMTP client.
A common alternate for the bulk mail rejection message is "4.7.1 451
Access denied by DCC" to tell the sending mail system to continue
trying. Use a 4yz response with caution, because it is likely to
delay for days a delivery failure message for false positives. If
the rejection message does not start with an RFC 1893 status code
and RFC 2821 reply code, 5.7.1 and 550 or 4.2.1 and 452 are used.
See also -B set:rej-msg=rejection-msg to set the status message for
mail rejected by DNS blacklist.
-j maxjobs
limits the number of simultaneous requests from sendmail that will
be processed. The default value of maxjobs is the maximum number
that seems to be possible given the number of open files, select()
bit masks, and so forth that are available, but at most 200.
Start dccm with -d and see the starting message in the system log to
see the limit.
-B dnsbl-option
enables DNS blacklist checks of the SMTP client IP address, SMTP
envelope Mail_From sender domain name, and of host names in URLs in
the message body. Body URL blacklisting has too many false posi-
tives to use on abuse mailboxes. It is less effective than
greylisting with dccm(8) or dccifd(8) but can be useful in situa-
tions where greylisting cannot be used.
Dnsbl-option is either of the forms set:option or
domain[,IPaddr[,bltype]]. Domain is a DNS blacklist domain such as
example.com that will be searched. IPaddr is the string "any" or
the IP address in the DNS blacklist that indicates that the mail
message is spam. 127.0.0.2 is assumed if IPaddr is absent. IPv6
addresses can be specified with the usual colon (:) notation. Names
can be used instead of numeric addresses. The type of DNS blacklist
is specified by bltype as name, IPv4, or IPv6. Given an envelope
sender domain name or a domain name in a URL of spam.domain.org and
a blacklist of type name, spam.domain.org.example.com will be tried.
Blacklist types of IPv4 and IPv6 require that the domain name in a
URL be resolved into an IPv4 or IPv6 address. The address is then
written as a reversed string of decimal octets to check the DNS
blacklist, as in 2.0.0.127.example.com,
More than one blacklist can be specified. They are searched in
order. All searching is stopped at the first positive result.
Positive results are ignored after being logged unless an
option DNSBL-on line appears in the global or per-user whiteclnt
file.
-B set:debug=X
sets the DNS blacklist logging level
-B set:msg-secs=S
limits dccm to S seconds total for checking all DNS blacklists.
The default is 25.
-B set:URL-secs=S
limits dccm to at most S seconds resolving and checking any
single URL. The default is 11. Some spam contains dozens of
URLs and that some "spamvertised" URLs contain host names that
need minutes to resolve. Busy mail systems cannot afford to
spend minutes checking each incoming mail message. In order to
use typical single-threaded DNS resolver libraries, dccm(8) and
dccifd(8) use fleets of helper processes.
-B set:no-envelope
says that SMTP client IP addresses and sender Mail_From domain
names should not be checked in the following blacklists. -B
set:envelope restores the default for subsequently named black-
lists.
-B set:no-body
says that URLs in the message body should not be checked in the
in the following blacklists. -B set:body restores the default
for later blacklists.
-B set:no-MX
says MX servers of sender Mail_From domain names and host names
in URLs should not be checked in the following blacklists. -B
set:MX restores the default.
-B set:rej-msg=rejection-msg
sets the SMTP rejection message for the following blacklists.
Rejection-msg must be in the same format as for -r. If
rejection-msg is the zero length string, the default is
restored. The default DNS blacklist rejection message is the
first message set with -r.
-X xfltr-option
controls the local external filter used by dccm(8), dccifd(8), and
dccproc(8). The external filter must be built into the DCC client
programs with ./configure --with-xfltr=FILE
Xfltr-option is either a string given the wrapper for the external
filter or of the form set:option.
Positive results from the external filter are ignore after being
logged unless an option xfltr-on line appears in the global or per-
user whiteclnt file.
-X set:debug=X
sets the external filter logging level
-X set:msg-secs=S
limits the time dccm will wait for an answer from the external
filter to S seconds. The default is 20.
-L ltype,facility.level
specifies how messages should be logged. Ltype must be error or
info to indicate which of the two types of messages are being con-
trolled. Level must be a syslog(3) level among EMERG, ALERT, CRIT,
ERR, WARNING, NOTICE, INFO, and DEBUG. Facility must be among AUTH,
AUTHPRIV, CRON, DAEMON, FTP, KERN, LPR, MAIL, NEWS, USER, UUCP, and
LOCAL0 through LOCAL7. The default is equivalent to
-L info,MAIL.NOTICE -L error,MAIL.ERR
dccm normally sends counts of mail rejected and so forth the to system
log at midnight. The SIGUSR1 signal sends an immediate report to the
system log. They will be repeated every 24 hours instead of at midnight.
Sendmail can affect dccm with the values of some sendmail.cf macros.
These macro names must be added to the Milter.macros option statements in
sendmail.cf as in the example "Feature" file dcc.m4.
${dcc_isspam} causes a mail message to be reported to the DCC server as
having been addressed to "MANY" recipients. The
${dcc_isspam} macro is ignored if the ${dcc_notspam} macro
is set to a non-null string
If the value of the ${dcc_isspam} is null, dccm uses SMTP
rejection messages controlled by -a and -r. If the value
of the ${dcc_isspam} macro starts with "DISCARD", the mail
message is silently discarded as with -a DISCARD. This can
be handy for keeping "spammers" from knowing they are
sending to "spam traps." If value of the macro not null
and does not start with "DISCARD", it is used as the SMTP
error message given to the SMTP client trying to send the
rejected message. The message starts with an optional
SMTP error type and number followed by text.
The -a option does not effect messages marked spam with
${dcc_isspam}. When the ${dcc_isspam} macro is set, the
message is rejected or discarded despite local or DCC
database white-list entries. The local white-list does
control whether the message's checksums will be reported
to the DCC server and an X-DCC SMTP header line will be
added.
${dcc_notspam}
causes a message not be considered unsolicited bulk
despite evidence to the contrary. It also prevents dccm
from reporting the checksums of the message to the DCC
server and from adding an X-DCC header line.
When the macro is set by the sendmail.cf rules,
${dcc_notspam} macros overrides DCC threshlds that say the
message should be rejected as well as the effects of the
${dcc_isspam} macro.
${dcc_mail_host}
specifies the name of the SMTP client that is sending the
message. This macro is usually the same as the mail_host
macro. They can differ when a sendmail "smart relay" is
involved. The ${dcc_mail_host} macro does not work if
FEATURE(delay_checks) is used.
${dcc_userdir}
is the per-user whitelist and log directory for a recipi-
ent. If the macro is not set in sendmail.cf,
$&{rcpt_mailer}/$&{rcpt_addr} is assumed,but with the
recipient address converted to lower case. Whatever value
is used, the directory name after the last slash (/) char-
acter is converted to lower case. Any value containing
the string "/../" is ignored.
This macro also does work if FEATURE(delay_checks) is
used.
The following two lines in a sendmail mc file have the
same effect as not defining the ${dcc_userdir} macro, pro-
vided FEATURE(dcc) is also used and the sendmail
cf/feature directory has a symbolic link to the
misc/dcc.m4 file.
SLocal_check_rcpt
R$* $: $1 $(macro {dcc_userdir} $@ $&{rcpt_mailer}/$&{rcpt_addr} $))
/var/lib/dcc is the DCC home directory in which other files are found.
libexec/start-dccm
is a script often used to the daemon.
dcc/dcc_conf
contains parameters used by the scripts to start DCC daemons
and cron jobs.
logdir is an optional directory specified with -l and containing
marked mail. Each file in the directory contains one message,
at least one of whose checksums reached its -t thresholds or
that is interesting for some other reason. Each file starts
with lines containing the date when the message was received,
the IP address of the SMTP client, and SMTP envelope values.
Those lines are followed by the body of the SMTP message
including its header as it was received by sendmail and with-
out any new or changed header lines. Only approximately the
first 32 KBytes of the body are recorded unless modified by
./configure --with-max-log-size=xx The checksums for the mes-
sage follow the body. They are followed by lines indicating
that the ${dcc_isspam} or ${dcc_notspam} sendmail.cf macros
were set or one of the checksums is white- or blacklisted by
the -w whiteclnt file. Each file ends with the X-DCC header
line added to the message and the disposition of the message
including SMTP status message if appropriate.
map is the memory mapped file of information concerning DCC
servers in the DCC home directory.
whiteclnt contains the client whitelist in the format described in
dcc(8).
whiteclnt.dccw
is a memory mapped hash table of the whiteclnt file.
dccm.pid in the -R rundir directory contains daemon's process ID. The
string ``dccm'' is replaced by the file name containing the
daemon to facilitate running multiple daemons, probably con-
nected to remote instances of sendmail using TCP/IP instead of
a UNIX domain socket. See also -R.
/var/run/dcc/dccm
is the default UNIX domain socket used by the sendmail milter
interface. See also -R.
sendmail.cf
is the sendmail(8) control file.
misc/dcc.m4
sendmail mc file that should have a symbolic link in the send-
mail cf/feature directory so that FEATURE(dcc) can be used in
a sendmail mc file.
Dccm should be started before sendmail with something like the script
libexec/start-dccm. It looks for common DCC parameters in the dcc_conf
file in the DCC home directory.
Those numbers should modified to fit local conditions. It might be wise
to replace the "100" numbers with much larger values or with "MANY" until
a few weeks of monitoring the log directory show that sources of mailing
lists are in the server's whitelist file (see dccd(8)) or the local
whiteclnt file.
It is usually necessary to regularly delete old log files with a script
like libexec/cron-dccd.
Sendmail must be built with the milter interface, such as by creating a
devtools/Site/site.config.m4 or similar file containing something like
the following lines:
APPENDDEF(`conf_sendmail_ENVDEF', `-D_FFR_MILTER=1')
APPENDDEF(`conf_libmilter_ENVDEF', `-D_FFR_MILTER=1')
Appropriate lines invoking the milter interface must be added to
sendmail.cf. It should be sufficient to copy the dcc.m4 file to the send-
mail 8.11 cf/feature directory and add the line
FEATURE(dcc)
to the local .mc file.
cdcc(8), dbclean(8), dcc(8), dccd(8), dblist(8), dccifd(8), dccproc(8),
dccsight(8), sendmail(8).
Implementation of dccm was started at Rhyolite Software in 2000. This
describes version 1.3.42.
dccm uses -t where dccproc(8) uses -c.
Systems without setrlimit(2) and getrlimit(2) RLIMIT_NOFILE can have
problems with the default limit on the number of simultaneous jobs, the
value of -j. Every job requires four open files. These problems are
usually seen with errors messages that say something like
dccm[24448]: DCC: accept() returned invalid socket
A fix is to use a smaller value for -j or to allow dccm to open more
files. Sendmail version 8.13 and later can be told to poll() instead of
select with SM_CONF_POLL. Some older versions of sendmail knew about
FFR_USE_POLL. One of the following lines in your devtools/Site/site.con-
fig.m4 file can help:
APPENDDEF(`conf_libmilter_ENVDEF', `-DSM_CONF_POLL')
APPENDDEF(`conf_libmilter_ENVDEF', `-DFFR_USE_POLL')
On many systems with sendmail 8.11.3 and preceding, a bug in the sendmail
milter mechanism causes dccm to die with a core file when given a signal.
August 1, 2006
Man(1) output converted with
man2html
modified for the DCC $Date 2001/04/29 03:22:18 $