gnarwl is an email autoresponder, intended to be a successor to the old
vaction(1) program. Since a modern mailserver, usually serves hundreds
(or even thousands) of mailaccounts, it is not sensible to give
(untrusted) users shell access so they may create/maintain the .forward file,
required by
vacation(1) . With
gnarwl , all user-suplied data is stored within an LDAP database, so
there are no per user ".forward" files (or even homedirs) needed.
Configuration is conveniently done via one systemwide configfile.
Like the old
vacation(1) program, gnarwl accepts incomming mail through
stdin, and will send outgoing mail via an external MTA (it even maintains
basic commandline compatibility, so it may be used as a drop in
replacement).
Several gdbm databases are maintained, in order to make sure, a) mail does not
bounce back and force between gnarwl and another automated MUA, b) mailing
lists will not be bothered and c) specifc local addresses may never produce
automatic replies.
All these database files may be managed using the
damnit(8) program.
OPTIONS
"-c
Use a different configfile than the one, compiled in.
"-a
Force <address> as receiving address.
"-s
Force <address> as sending address.
-h
Print usage information.
CONFIGURATION
gnarwl typically uses one global configurationfile, but a per user setup is also
possible using the -c commandline switch. The following keywords are
recognized in the configfile:
"map_sender
Binds a macroname (case insensitive), refering to the sender of an incomming
email. Defaults to "$sender".
"map_receiver
Binds a macroname (case insensitive), refering to the receiver(s) of an
incomming email. Defaults to "$receiver".
"map_subject
Binds a macroname (case insensitive), refering to the subject of an incomming
email. Defaults to "$subject".
"map_field
Binds a macroname (case insensitive), refering to a field in the resultset,
returned by the database. There are no defaults for this directive.
"server
Address of the databaseserver to query. Defaults to localhost.
"port
Port, the LDAP server listens on. Defaults to 389.
"scope
The scope used for searching the database. Default is "sub".
"login
Destinguished name to bind with to the LDAP database. Default is to bind
anonymously.
"password
Password to use for binding to the LDAP database. If a password is required
to access the server, then the configfile should belong to the gnarwl user
and have file permission 0400.
"base
Entrypoint of the search. There is no default for this directive, it must
be supplied by the administrator.
"protocol <0|2|3>
Select protocol to bind to the ldapserver. The default is 0, which means
"autodetect".
"queryfilter
Search pattern to match against the database. Defaults to:
"(&(mail=$recepient)(vacationActive=TRUE)".
"result
The name of the attribute, that is to be taken as the emailbody. The content
of this field will be pasted in between the data found via forceheader and
forcefooter directives. Afterwards all remaining macros are expanded in the
order of declaration, and the result will be piped through to the MTA.
"blockfiles
The directory, where gnarwl stores it's blockfiles. These files are
required to keep track on who was sent an automatic reply. Default is:
"/var/lib/gnarwl/block/".
"umask <mode>
What permission to give newly generated database files. The default is
0600.
"blockexpire
How long (in hours) to block a certain sender/recepient combo. Default is
48 hours. Setting <number> to 0 disables the feature (not recommended). No
blockfiles are read/written in this case.
"maxreceivers
Ignore incomming email, specifying too many receiving addresses. It does
not matter, whether these are local or not, as
gnarwl doesn't know domains. Default is 256.
"maxheader
Ignore incomming email with more than this number of header lines. Lines are
counted before unfolding them, so a folded line really counts as at least
two lines. Default is 256.
"badheaders
Path to a database file, containing matching patterns for the mailheader.
If an entry stored in this file matches a line in the header exactly, then
this mail will be ignored by
gnarwl is deactivated by default.
"blacklist
Pointer to a database file, containing emailaddresses,
gnarwl is not allowed
to generate automatic replies for (useful to prevent automatic replies from
addresses, which are shared by several people). This feature is deactivated
by default.
"forceheader
Path to a text file, containing a standardized header, that is to be
pasted in front of every outgoing mail. This file should end with a single
empty line. Otherwise it is assumed, that the users are allowed to
continue the header and will provide the separating empty line themselves.
Default is not to force anything (that is: The user has to supply the header
in the "result" attribute).
"forcefooter
Path to a text file, containing a standardized footer, that is to be appended
at the end of every generated mail. Default is to not to force anything.
"mta
Specify MTA for sending mail. It must be able to accept mail on STDIN.
Default is "/usr/sbin/sendmail".
"charset
LDAP stores text in unicode, which is ok, as long as outgoing mail doesn't
contain any non ASCII characters. However, locale specific characters (like
german umlaute) end up as strange glyphs. With the "charset" directive,
gnarwl tries to convert these to the correct symbols. The <encoding> argument
must contain a string recognized by iconv(3) .
Default is not to try to convert anything (assume US-ASCII charset / MIME
encoded mail).
"recvheader
A whitespace separated list of headers (case does not matter), which may
contain receiving addresses. Defaults to: "To Cc".
"loglevel
Specifies what to send to the syslog. A higher loglevel
automatically includes all lower loglevels (see section syslog for more
information).
SYSLOG
Since
gnarwl is not meant to be invoked by anything but the mailsystem,
it'll never print out messages to the systemconsole, but logs them via
syslog(3) , using the facility "mail". A log line is always of the following
format:
<level>/<origin> <message>
The <level> field indicates the severity of the message, it corresponds to the
"loglevel" config directive. Possible values are:
"CRIT
Critical messages.
gnarwl cannot continue and will die with a non-zero exit code. This usually causes the mailsystem to bounce mail.
"WARN
A warning.
gnarwl can will continue, but not with the full/intended functionality.
"INFO
Status information. A message in the INFO loglevel indicates normal
behaviour.
"DEBUG
Debugging information.
gnarwl will log a lot of information on how mail is processed.
The <origin> field gives a short hint about what caused the log entry in
question, while <message> contains a short description of what actually
happened.
