Sophie: mailfilter-0.2.4-1mdk i586

mailfilter-0.2.4-1mdk.i586.rpm

Mailfilter Frequently Asked Questions and Answers

------------------------------------------------------------------------

General Questions:

* What is Mailfilter?
* Who needs Mailfilter?
* How does Mailfilter interact with my current e-mail environment?
* Where do I find out more about Mailfilter?
* I think, I found a bug in Mailfilter. Will you fix it?
* I have good ideas for new features. Will you implement them?

Installation:

* What are the system's requirements to install and run Mailfilter?
* What should I know to make Mailfilter run on Windows 9x/2000/NT?
* How do I install Mailfilter?
* Running 'configure' doesn't work.
* Running 'make' doesn't work.
* Running 'make' was easy, but running 'make install' doesn't work.
* Is there any way to decrease the size of the mailfilter binary?

Configuration:

* Mailfilter complains that its rcfile (~/.mailfilterrc) is missing.
* Mailfilter complains that its logfile can't be accessed.
* Mailfilter complains about the syntax of my rcfile.
* How do these filters work? What are Regular Expressions anyway?
* Is it possible to define what should be delivered, rather than vice
versa?
* Can I override some filters? (How to define 'friends'/trusted lists)
* How do I get rid of messages sent in exotic (e.g. Asian) languages
(unknown to me)?
* How do I fine tune other programs to work with Mailfilter?
* I'm using multidrop mail collection with fetchmail and can't get
Mailfilter to work.
* Are there any sample rcfiles (~/.mailfilterrc) ?
* I am scared to try out Mailfilter, cause I might accidently delete
everything!

Run-time Errors:

* Because of some missing libraries, Mailfilter won't start.
* Mailfilter complains that a specific file couldn't be accessed.
* I get DNS lookup errors.
* Mailfilter says it sent a specific command to the server, but it
responded with an error.
* Mailfilter says that some keyword is deprecated.
* The compilation of Regular Expressions failed.
* I frequently get an error message saying that my mail server is not
responding.
* Help, Mailfilter hangs!

Special Features:

* Can Mailfilter check more than one account?
* Does Mailfilter support any other protocols besides POP3?
* Is there a way to send encrypted password information to the server?
* How can I get Mailfilter to auto-reply to spam?

Miscellaneous:

* I think I accidently deleted an important e-mail with Mailfilter. Can I
get it back somehow?
* If I make changes to rcfile, does it affect immediately?
* Sometimes a few (spam-) messages slip through. How come?
* My question is not covered by this FAQ. Help!!

------------------------------------------------------------------------

General Questions:

* What is Mailfilter?

Mailfilter is a flexible utility for UNIX (-like) operating systems to
get rid of unwanted spam mails, before having to go through the trouble
of downloading them into the local computer. It offers support for one
or many POP3 accounts and is especially useful for dialup connections
via modem, ISDN, etc.
Mailfilter connects to any POP3 mail box and compares part of its
content to a set of user defined filter rules. That way the spam gets
deleted directly on the mail server.
With Mailfilter you can define your own filters (rules) to determine
which e-mails should be delivered and which are considered waste. Rules
are Regular Expressions, so you can make use of familiar options from
other mail delivery programs such as e.g. procmail.
Mailfilter is released under the terms of the GNU General Public
License. For more information, see the README and COPYING documents
provided with the Mailfilter program.

* Who needs Mailfilter?

If you do not pick up your e-mail from a POP3 server, then there is no
need to install Mailfilter. But if you do get your e-mail from one or
many POP3 accounts and if you are sick and tired of downloading
megabytes of worthless spam (usually those are anonymous
advertisements, chain mails, etc.), then you should give Mailfilter a
try.
It will help save you band width and time by deleting spam directly on
your server, before you have to download and read those messages. By
defining your own personal filter rules, you can tell Mailfilter which
e-mails should be deleted.

* How does Mailfilter interact with my current e-mail environment?

It doesn't matter which programs you use to fetch your mail with,
because Mailfilter is an independent application. It will not interfere
with your favourite e-mail client. You may just want to start
Mailfilter everytime you are about to download new e-mail from a POP3
server, or maybe just once a day. That's entirely up to you.
However, if you are using highly configurable mail programs such as
fetchmail, then there are some clever ways to get Mailfilter cooperate
with them directly. Section "How do I fine tune other programs to work
with Mailfilter?" describes this in more detail.

* Where do I find out more about Mailfilter?

All relevant documentation for Mailfilter (including this FAQ) is
provided with the Mailfilter distribution. Online versions of some of
these documents are available on the official Mailfilter homepage:

http://mailfilter.sourceforge.net/

On this homepage you may also find additional information on Regular
Expressions and related links to other programs that work well with
Mailfilter. If you have already installed the program, be sure to read
the man pages mailfilter(1), mailfilterrc(5) and mailfilterex(5).

* I think, I found a bug in Mailfilter. Will you fix it?

If it's really a bug that you found (and not a feature), then I will of
course try to do something about it. Generally it's a good idea to
report bugs to the mailing list mailfilter-dev@lists.sourceforge.net,
but you can also directly contact the author of Mailfilter. When you
report bugs, please provide as much additional information as possible
on what may have caused the problems and what consequences you
suffered. Such information always includes the name of your operating
system and hardware platform, description of your network connection
and excerpts from the Mailfilter log files. When creating a log file,
please use the highest level of verbosity available.

mailfilter --verbose=6

Older versions of Mailfilter do not hide your passwords in the logs.
Remove these entries before posting anything to the mailing list!

* I have good ideas for new features. Will you implement them?

Of course that depends on the feature you are asking for. There are
some frequently requested features ('autoreply' ranks very high) that
will most likely never make it into the source code, but at this point
I am sure Mailfilter could be expanded with dozens of useful additions
and I'm glad to hear about them (if they are not too far 'off the
track'). I'm even more glad if you're able to help implement them.

------------------------------------------------------------------------

Installation:

* What are the system's requirements to install and run Mailfilter?

Here is an excerpt from the INSTALL file that is part of the source
archive of Mailfilter:

To run Mailfilter it's best to have a UNIX (-like) operating system, but it
also compiles fine with Windows 9x/NT/2000 if additional libraries and tools
are installed (e.g. Cygwin or DJGPP). So far Mailfilter has been successfully
compiled and tested with

- Solaris 8 / SunOS 5.8

- Irix 6.5

- FreeBSD 4.1.1-RELEASE

- Mac OS X

- NetBSD 1.5

- Linux: Mandrake 7.0 - 8.1, Debian 2.1, RedHat 6.2 - 7.1,
Slackware 3.9 (See README.Slackware for further details)
SuSE 6.2, LinuxPPC

- Windows NT (See README.Windows for further details)

but it may well work on other platforms, too. (Please report success if you
have managed to compile it on any other system - thanks.)

To install Mailfilter you also need to have a fairly recent version of the
GNU C++ compiler (e.g. 2.95.x) and your system must support BSD-type sockets
(in general all UNIX systems do meet this criterion).

* What should I know to make Mailfilter run on Windows 9x/2000/NT?

Mailfilter was originally designed to only support UNIX (-like)
operating systems. But if you have additional libraries such as the
Cygwin environment, DJGPP or MinGW installed, then you should also be
able to translate the program on your Windows 9x/2000/NT platform. Have
a look at the README.Windows file that comes with the Mailfilter
distribution or consult the homepage for additional information and
pre-compiled binaries.

* How do I install Mailfilter?

If you have downloaded the compressed Mailfilter source code archive,
then please refer to the INSTALL file provided by that archive. Binary
packages (if available for a particular program version) should be
installed as any other package of that kind. For example you could use
the command 'rpm -U packagename.rpm' for the RedHat packages.
Note: even if you did not encounter any problems installing the
program, I strongly recommend reading the INSTALL file anyway in order
to find out about the set-up of Mailfilter. The program does not work
without spending a little bit of time on configuration first.

* Running 'configure' doesn't work.

If your system lacks some of the requested
features/libraries/compilers, then try installing them and run
'configure' again. But don't forget to remove the file config.cache
first, or the new components can not be found. If it's a more serious
problem that can't be fixed that way, consider reporting it as bug.

* Running 'make' doesn't work.

The most common reason why 'make' fails is that your system does not
offer a recent version of the GNU C++ compiler (gcc) or its libraries.
Releases prior 2.95.x don't know C++ namespaces and therefore choke on
Mailfilter's source code. Updating your compiler should fix these sorts
of problems. Also note that Mailfilter needs a standard C compiler to
translate additional C source code.

* Running 'make' was easy, but running 'make install' doesn't work.

The most common cause for this behaviour is that you are trying to
install Mailfilter into a directory where you do not have the necessary
permissions to write in. Either reconfigure your Makefile with these
options

make clean
./configure --prefix=/newdir

where 'newdir' points to the new location for Mailfilter, or simply
become 'root' and then run 'make install' again. By default this will
install the software in /usr/local/bin.

* Is there any way to decrease the size of the Mailfilter binary?

For users of UNIX-like systems, yes. When installing the program,
running 'make install-strip' instead of 'make install' will strip the
binary as it installs it, drastically decreasing its size.
If you've already installed mailfilter, but still wish to strip the
binary, become root, and use the strip command. See the manual page of
strip(1) for more information.

------------------------------------------------------------------------

Configuration:

* Mailfilter complains that its rcfile (~/.mailfilterrc) is missing.

Read the INSTALL file provided with Mailfilter, in which you will find
an example rcfile set-up. Copy and paste this example, modify it to
suit your own needs and restart Mailfilter. (Alternatively you can also
look up the official homepage to find a basic set-up that gets you
started very conveniently.) If the program still complains, then try to
start it with the '--mailfilterrc' switch, pointing directly to the new
location of your rcfile.
Note: you must have a rcfile file installed somewhere.

* Mailfilter complains that its logfile can't be accessed.

Every rcfile must set the LOGFILE option. Check the given path of your
logfile in the rcfile, or simply start Mailfilter with the '--logfile'
switch pointing directly to the desired location. If that doesn't help,
then check the permissions of the directory where you want Mailfilter
to store its logs in. It has to be writable.

* Mailfilter complains about the syntax of my rcfile.

Not to worry, you probably misspelled a word or two in the rcfile, or
you have a couple of 'spaces' hidden somewhere. Read through it
carefully and keep in mind that the commands are case sensitive.
Therefore it does matter whether you say 'DENY' or 'Deny' (which would
cause a program failure). Typically an entry in ~/.mailfilterrc looks
like this

SERVER=myserver.domain.com

Commands must be written in capitals, followed by a '=' and there are
no spaces in between or after. Each command has to be in a separate
line.

* How do these filters work? What are Regular Expressions anyway?

With Mailfilter you can define your own filter rules to determine which
e-mails are considered waste and what should be downloaded into your
local computer. Such rules are defined by using Regular Expressions. It
is very common for these kinds of programs to employ this technique
because of its great flexibility. Consider this simple example: if you
are not interested to get the 200th advertisement containing
information about Viagra, you might want to add this to the end of your
rcfile

DENY=^Subject:.*Viagra

Now every e-mail that contains anything about Viagra in the subject
line gets deleted right away. You can create similar rules for all of
the other header fields (cc, To, From, etc.), but be aware of the fact
that Mailfilter does not allow more than one line per rule. So each new
filter must be placed in its own line starting with 'DENY='. If you
don't want the filter rules to be case-sensitive then you also have to
add this line to your rcfile:

REG_CASE=no

A comprehensive list of all supported keywords can be found in the
mailfilterrc(5) man page. More examples and real-life use cases can be
looked up in the mailfilterex(5) man page. Study these documents
carefully! If you're eager to know how Regular Expressions work in
general, use your favourite UNIX book or have a look at the official
Mailfilter homepage. There you will find some enlightening links on
this subject.

* Is it possible to define what should be delivered, rather than vice
versa?

Yes, by creating a negative filter. Negative Filters are quite
restrictive, so you should make sure that you have fully understood how
these are set up and how they work.

DENY<>^(To|Cc):.*my-email@address\.com

Having a simple rule like this added to your rcfile, Mailfilter will
delete every message which is not directly sent to your e-mail account.
That is, if there is a message that can't be matched to the above, then
it automatically qualifies as spam.

* Can I override some filters? (How to define 'friends'/trusted lists)

Yes, using the keyword ALLOW you can define which messages should be
delivered, regardless of any spam filters that might match. This way
you can not only define 'friends' lists, but also create a very
restrictive rule set. Consider this example:

DENY=^From:.*@spam_isp.org
ALLOW=^From:.*my_friend@spam_isp.org

Adding these two lines to your rcfile will filter all messages coming
from the domain 'spam_isp.org', except for those from your friend
'my_friend' (who should obviously change his ISP). A comprehensive list
of all supported keywords can be found in the mailfilterrc(5) and
mailfilterex(5) man pages. Study them carefully!

* How do I get rid of messages sent in exotic (e.g. Asian) languages
(unknown to me)?

Spam is not only a European or American illness. In fact a lot of it
comes from Asia and a lot of that reaches people who can not read nor
understand what arrives in their mail boxes. The following filters will
help you to get rid of e-mails that contain 'unusual' subject tags.
Consider some excerpts from a typical logfile:

Subject: ¹²ÏíÂ·ÓÉÆ÷£¨ADSL/CABLE/ISDN/PSTN/SWITCH£©
Subject: Ç¿ÁÒÍÆ¼öÊôÓÚÄúµÄÍøÉÏÉçÇø£¡(www.I_am_a_Spammer.com)
Subject: 70ÍòÆóÒµÐÅÏ¢

All these subjects have one thing in common: They use characters which
do not fit into the ordinary range of displayable ASCII symbols. A
hexdump of the last subject line will help to illustrate this:

0000 53 75 62 6a 65 63 74 3a 20 37 30 cd f2 c6 f3 d2 Subject: 70ÍòÆóÒ
^^ ^^ ^^ ^^ ^^
0010 b5 d0 c5 cf a2 µÐÅÏ¢
^^ ^^ ^^ ^^ ^^

Even though it is possible to create filters matching these strings, it
takes a bit of work, since Mailfilter uses a Regular Expression library
that does not support octal or hex escapes (something like
[\x80-\xfc]). In fact, the negative (and case sensitive) message
filters are our weapon of choice here:

DENY_CASE<>=^Subject: [][A-Za-z0-9ÄÖÜäöüß:;.,!"§$%&/()=?{}_<>#~´'` |@*+°^\-]+$
^ ^^ ^^^^^^^ ^^ ^^^^
1 23 4 5 6278

There are some important issues in this expression, numbered from 1 -
8:

1. See 8.
2. These brackets '[]' enclose a character class.
3. We want to allow these brackets, too. The only position where to
put the closing bracket into a character class is the first one.
4. For those who want to allow German subjects. (Modify this to fit
your own needs for Scandinavian languages, etc.)
5. Attention: There are two different single quotes from the upper
right to the lower left.
6. Inside a character class the hyphen '-' is a meta symbol to set a
range of characters (take a look at the beginning). In order to
get the actual literal '-', it must be positioned at the end of
the class.
7. Indicates that the preceding character or character class has to
be present at least once.
8. In order to force the mail's originator to only use these
characters in the subject line, there must not exist any preceding
or following characters. That is the preceding character has to be
the start of the line, the following character has to be the end
of the line.

To make Mailfilter's Regular Expression compiler accept the above
filter you need to switch off the locale first ('handling of different
country characteristics'). If you are calling a script for filtering
and getting messages, you could use something similar to this:

#!/bin/sh

# Remove locale
L=$LANG
unset LANG

# Get mails
/usr/local/bin/fetchmail $*

# Restore locale
LANG=$L

Alternatively it is also possible to create a straight forward filter
that matches non-ISO-8859-1 messages (or at least almost). The standard
ISO-8859-1 is an extension to the ASCII character set (i.e. the first
128 characters are the same, greater numbers encode symbols, accents,
etc.) and supports the following languages: Afrikaans, Basque, Catalan,
Danish, Dutch, English, Faeroese, Finnish, French, Galician, German,
Icelandic, Irish, Italian, Norwegian, Portuguese, Spanish and Swedish.
There is a draw back though: the filter we're presenting here accepts
only special German characters (umlauts) as extension and is therefore
not fully ISO-8859-1 compliant. However, you might consider it useful
anyway.

# A filter that only accepts ASCII characters and also German umlauts as extension
DENY_NOCASE=^Subject:.*=\?ISO-8859-1\?Q\?.*=([0189][[:xdigit:]]|[7F]F|A[0189A-F]|B[1235-9A-F]|[CE][0-35-9A-F]|[DF][0-5789ABDE])

Needless to say, you need to have extended Regular Expressions enabled
(Mailfilter's default are basic expressions) in order to create such
complex rules. (This truly frequently asked question was patiently
worked out and answered by Til Schubbe.)

* How do I fine tune other programs to work with Mailfilter?

As always, there are various ways to achieve this. I have chosen the
commonly used application fetchmail to explain how this works. (Similar
options are available in other mail programs, such as Kmail or
Evolution.) Fetchmail is a nifty program that downloads e-mail from
POP3 accounts (it also supports other protocols). Therefore it's a very
tempting idea to use the clean up services of Mailfilter before we're
starting to receive huge amounts of junk in between our normal e-mail
messages. Adding one single line to the fetchmail set-up file does the
trick:

poll my.mailserver.de via "my.mailserver.de"
with proto POP3
localdomains mailserver.de
user "username" there with password "pass" is tuxuser here options forcecr warnings 3600
preconnect "mailfilter"

poll my2.mailserver.de via "my2.mailserver.de"
with proto POP3
localdomains mailserver.de
user "anotherusername" there with password "other_pass" is tuxuser here options forcecr warnings 3600

The line 'preconnect "mailfilter"' tells fetchmail to invoke Mailfilter
each time the user requests the download of new e-mail messages. If
Mailfilter is set up to check both of the given accounts then calling
it merely once is sufficient.
Another very good (and popular) way of using Mailfilter is to call it
via cron, or just once upon login. That way you won't see much of it
either and can work with your favourite e-mail program just as you are
used to - except you won't be disturbed by spam anymore.

* I'm using multidrop mail collection with fetchmail and can't get
Mailfilter to work.

Peter T. Garner contributed this one: consider an environment in which
six users collect mail via fetchmail's multidrop mechanism, but want
their messages checked for spam first. That's no problem if you mind
the right syntax and add something like this to your fetchmail set-up:

set postmaster "root"
set properties ""
set bouncemail
set syslog
poll pop.something.net with proto POP3
envelope Envelope-to
aka something.rather.co.uk
user anything.anyone.co.uk there with password TOP_SECRET
to
peterg = peterg
annie = annie
gemma = gemma
lizzy = lizzy
bob = bob
here
options
preconnect "mailfilter --mailfilterrc=/etc/mailfilter.rc"

* Are there any sample rcfiles (~/.mailfilterrc) ?

Yes, there are. You can find one in the INSTALL guide provided with
Mailfilter, or check the rest of the documentation for additional
'rcfile.example' files. A comprehensive list of all supported keywords
can be found in the mailfilterrc(5) and mailfilterex(5) man pages.
Study them carefully!

* I am scared to try out Mailfilter, cause I might accidently delete
everything!

No, you won't. If you are new to Mailfilter, place this line in your
rcfile before running the program for the very first time:

TEST=yes

This makes sure you are not losing any mail at all, including spam.
When Mailfilter is in test mode it only simulates the deletion of
e-mail and you can see how good your filters would work - in theory.
Once you have come to a point where you are happy about their behaviour
you can remove this command from your rcfile again and start to
seriously kill the spam.

------------------------------------------------------------------------

Run-time Errors:

* Because of some missing libraries, Mailfilter won't start.

So far I have only witnessed this behaviour on a poorly administered
Solaris machine. If you get an error message similar to this

ld.so.1: ./mailfilter: fatal: libstdc++.so.2.10.0: open failed: No such
file or directory

then your library path is not set properly. To fix the problem, simply
type something like this in your shell (if it's bash - otherwise you
may have to use 'set' instead of 'export') depending on the path of
your libraries (sometimes they're also in /opt/lib)

export LD_LIBRARY_PATH=/usr/lib:/usr/local/lib:$LD_LIBRARY_PATH

* Mailfilter complains that a specific file couldn't be accessed.

Most likely you need to fix up your Mailfilter configuration. Please
refer to the "Configuration" section in this FAQ.

* I get DNS lookup errors.

Such errors occur when the Domain Name Server failed to resolve the
name of your POP3 server. This either happens when you have misspelled
the server name in your rcfile, or when you are trying to start
Mailfilter even though you have not established a network connection
first.

* Mailfilter says it sent a specific command to the server, but it
responded with an error.

Usually these errors occur when you are trying to get your mail from a
server that does not fully support the POP3 transfer protocol. But you
can also get this behaviour if your network connection (or only the
connection to the POP3 server) drops during a mail box examination. In
this case, simply try to invoke Mailfilter again. If that doesn't fix
it, consider reporting a bug.

* Mailfilter says that some keyword is deprecated.

This may happen occasionally when updating from an old version of
Mailfilter to a new one. Usually the program suggests a new keyword in
its error message though. But you can also look up the proper
definition in the documentation files that come with the Mailfilter
distribution, or consult the mailfilterrc(5) man page. It contains a
comprehensive list of all supported and deprecated keywords.

* The compilation of Regular Expressions failed.

Extended Regular Expressions are not 100% compatible to the basic kind
of expressions. Check if you have set Mailfilter to support extended
expressions (keyword REG_TYPE) and adjust your filters if necessary.
Another reason could be the Cygwin environment, if you encounter this
error on a Microsoft Windows platform. We are working on it, but please
submit a bug report anyway, so we can get as much information about
this problem as possible. Thank you.

* I frequently get an error message saying that my mail server is not
responding.

You have to use the keyword TIMEOUT in order to increase the response
time out value. The default is set to 30 seconds, but in some occasions
a higher value might be necessary, because some mail servers take
longer to send a response, than others. This behaviour can also be
experienced on slow or extremely busy network connections.

* Help, Mailfilter hangs!

Depending on your machine's operating system and configuration you
might run into trouble with the deployed Regular Expression library.
Mailfilter depends on that component to match the user defined spam
filters.
It has been reported that certain library implementations do not like
large strings and therefore stop Mailfilter when it tries to process
e-mails with big headers. The Internet standard RFC 822 explicitly
forbids any header description to exceed the 998 byte limit. So, you
should use the MAXLENGTH keyword in your rcfile to make sure no strings
larger than 998 characters are being processed by Mailfilter. All the
different Regular Expression libraries should be able to happily handle
that size, too.

------------------------------------------------------------------------

Special Features:

* Can Mailfilter check more than one account?

Of course it can. Personally, I despise all e-mail programs that have
such stupid limitations. How many users nowadays have only one account
anyway?

* Does Mailfilter support any other protocols besides POP3?

Not in the current version, but support for the IMAP protocol is
planned.

* Is there a way to send encrypted password information to the server?

Not in the current version. This is another feature that I will look
into though.

* How can I get Mailfilter to auto-reply to spam?

You can't and this is a feature that will never be implemented either.
I started the Mailfilter project to prevent e-mail abuse in general not
to give people a weapon to fight fire with fire. Apart from that it
would be considered a criminal offense in most countries (including the
one I'm living in) to answer a mail bomb with your own mail bomb.

------------------------------------------------------------------------

Miscellaneous:

* I think I accidently deleted an important e-mail with Mailfilter. Can I
get it back somehow?

Tough. Once Mailfilter deleted an e-mail, all you get to see of it is
where it came from, what it was about and when it was sent. Have a look
in your logfile and ask the author to send it again. If that's not an
option for you, you may want to ask your ISP to recover this message
for you, though I doubt this would be a very successful undertaking.

* If I make changes to the rcfile, does it affect immediately?

If you are changing Mailfilter's settings while it's active, nothing
special will happen. All changes you make in the rcfile will be
considered next time you run the application.

* Sometimes a few (spam-) messages slip through. How come?

This is not a bug in Mailfilter. Consider this a feature of every POP3
e-mail server. Once you start checking for spam or downloading
messages, the server locks your mail box. If new messages arrive during
the locked state, they will be queued and provided for further
processing after the lock has been removed.
So Mailfilter does not see incoming messages while it checks for spam
and sometimes it happens that a message or two arrive just in time to
be too late for filtering, but in time for download. That's life.

* My question is not covered by this FAQ. Help!!

This FAQ can never be a 100% complete guide, covering all possible
aspects of the Mailfilter program. That is the reason why we have
created a mailing list where we discuss the various aspects of spam
killing and how to use Mailfilter. Feel free to subscribe and ask your
questions. In urgent or very special cases, however, you can also
contact me directly, the author of Mailfilter. Maybe the question will
be just another candidate for the FAQ.