jantypas@hope.UUCP (John Antypas) (10/06/86)
MEP the mail server for BSD systems which provides return receips
for mail and remote program execution and twitlists (weeds out mail
from people you don't want to here from) V.1.0 is now available
either through SIMTEL20 archives for ARPA people, or through the
archive server on Simtel for Usenet people -- or if you want you can
get it from me directly -- or rather from MEP.
Just send mail to me with the subject line = Command and
include the following in the message
@RR This is to get a return receipt
@SH mep <your path back from me>
MEP will mail itself back to you.
John Antypas
...!{ucbvax!ucdavis,sdcsvax}!ucrmath!hope!jantypasjantypas@hope.UUCP (John Antypas) (10/09/86)
Hello everyone it's me again. MEP has had some bug fixes so now it should work with people other than root. If you'd like the latest copies, please go through the sequence again, that is % Mail ...!ucbvax!ucdavis!hope!jantypas Subject: Command @RR @SH mep <return path> Note, we DO NOT run pathalias. We cannot accept aaddresses such as site.UUCP. It will die in my mailbox. Furthermore, although we call sdcsvax quite a bit -- the maps insist that we talk to ucla and to ucsd directly. Truth be told, ucla is far less reliable than ucsd. Please, if you must sdcsvax, and if you don't want to wait a bit, use ...!sdcsvax!explicit_path!ucrmath!hope!jantypas which will force it to go directly to us, , or use ucbvax!ucdavis!ucrmath or lll-crg!ucdavis!ucrmath!hope thanks. John Antypas ucbvax!ucdavis!ucrmath!hope!jantypas
taylor@hplabsc.UUCP (Dave Taylor) (12/02/86)
Another program that is part of the latest distribution of the Elm Mail System has a similar functionality - filter - and will be included in the upcoming release of the latest version in mod.sources (probably some time in January). To tantalize you all (evil laugh) I've attached the Filter Users Guide below.... -- Dave Taylor taylor@hplabs.HP.COM -- attachment: Filter Users Guide Elm Filter Guide What the filter program is, what it does, and how to use it One of the greatest problems with the burgeoning electronic mail explosion is that we tend to get mail that we don't care about. Amusingly, perhaps, we have the equivalent of electronic junk mail. Not amusing, however, is the fact that this can rapidly accumulate and end up tak- ing over your mailbox! At the same time we often get mail that, while it is interesting and important, can easily be filed to be read later, without ever actually cluttering up the mailbox. This, then, is what filter does for you! The filter program allows you to define a set of rules by which all incoming mail should be screened, and a subsequent set of actions to perform based on whether the rules were met or not. Filter also has the ability to mail a summary of what actions it performed on the incoming mail as often as you'd like. Writing the Rules The language for writing filter rules is pretty simple, actually. The fundamental structure is; if (condition) then action Where condition is constructed by an arbitrary number of individual conditions of the form ``field relation value''. The field value can be; subject from to lines contains where, if ``lines'' is choosen, the relation can be any of the standard relationships (`>', `<', `>=', `<=', `!=' and `='). If another action is choosen, ``contains'' can be used as the relation, ``='', or, if you'd like, you can skip the relationship entirely (e.g. `subject "joe"'). The value is any quoted string that is to be matched against or number if ``lines'' is the field being considered. Individual conditions are joined together by using the word ``and'', and the logic of a condition can be flipped by using ``not'' as the first word (e.g. `not subject "joe"'). We'll see more examples of this later. Note that the ``or'' logical conjunction isn't a valid part of the filter conditional statement. Finally, <action> can be any of; delete save foldername savecopy foldername forward address execute command leave where they result in the actions; delete deletes the mes- sage; save saves a copy of the message in the specified fol- dername; savecopy does the same as save, but also puts a copy in your mailbox; forward sends the message to the specified address; execute feeds the message to the speci- fied command (or complex sequence of commands) as standard input; and leave leaves the message in your mailbox. Foldernames can contain any of a number of macros, too, as we'll see in the example ruleset below. The macros avail- able for the string fields are; Macro Meaning %d day of the month %D day of the week (0-6) %h hour of the day (0-23) %m month of the year (0-11) %r return address of message %s subject of original message %S ``Re: subject of original message'' %t current hour and minute in HH:MM format %y year (last two digits) The rules file can also contain comments (any line starting with a `#') and blank lines. The file itself needs to reside in your home directory and be called .filter-rules. Here's an example; # $HOME/.filter-rules # # Filter rules for the Elm Filter program. Don't change without some # serious thought. (remember - order counts) # # Dave Taylor # rule 1 if (from contains "!uucp") then delete # rule 2 to "postmaster" ? save "/tmp/postmaster-mail.%d" # rule 3 if (to "culture" and lines > 20) ? save "/users/taylor/Mail/culture" # rule 4 subject = "filter test" ? forward "hpldat!taylor" # rule 5 if [ subject = "elm" ] savecopy "/users/taylor/Mail/elm-incoming" # rule 6 subject = "display-to-console" ? execute "cat - > /dev/console" (notice the loose syntax - there are lots of valid ways to specify a rule in the filter program!!) To translate these into English; 1. All messages from uucp should be summarily deleted. 2. All mail to postmaster should be saved in a folder (file) called /tmp/posmaster-mail.numeric-day-of-the- week 3. All mail addressed to `culture' with at least 20 lines should be automatically appended to the folder /users/taylor/Mail/culture. 4. All messages that contain the subject `filter test' should be forwarded to me, but via the address `hpldat!taylor' (to force a non-user forward) 5. All messages with a subject that contains the word `elm' should be saved in the folder ``/users/taylor/Mail/elm-incoming'' and also dropped into my mailbox. 6. Any message with the subject ``display-to-console'' will be immediately written to the console. Notice that the order of the rules is very important. If we, for example, were to get a message from `uucp' that had the subject `filter test', the filter program would match rule 1 and delete the message. It would never be forwarded to `hpldat!taylor'. It is for this reason that great care should be taken with the ordering of the rules. Checking the rules out The filter program has a convenient way of check out the rules you have written. Simply invoke it with the -r (rules) flag; % filter -r Rule 1: if (from = "!uucp") then Delete Rule 2: if (to = "postmaster") then Save /tmp/postmaster-mail.2 Rule 3: if (to = "culture" and lines > 20) then Save /users/taylor/Mail/culture Rule 4: if (subject = "filter test") then Forward hpldat!taylor Rule 5: if (subject="elm") then Copy and Save /users/taylor/Mail/elm-incoming Rule 6: if (subject="display-to-console") then Execute "cat - > /dev/console" There are a few things to notice - first off, these are the parsed and rebuilt rules, so we can see that they are all in a consistent format. Also, notice on the filename for rule 2 that the program has correctly expanded the ``%d'' macro to be the day of the month. It is highly recommended that you always check your ruleset before actually letting the program use it! Actually Using the Program Now the bad news. If you aren't running sendmail you cannot use this program as currently written. Why? Because the filter program expects to be put in your .forward file and that is something that only sendmail looks at! The format for the entry in the .forward file (located in your home directory) is simply; "|filter" Alright, it isn't quite that simple! Since filter will be invoked by processes that don't know where you are logged in, you need to have some way to trap the error messages. For ease of use, it was decided to have all the messages written to stderr which means that you have two main choices for the actual entry. Either; "|filter > /dev/console 2>&1" which will log all errors on the system console (each error is prefixed with ``filter (username)'' to distinguish it), or; "|filter >> $HOME/.filter_errors 2>&1" If you want to have a copy saved to a file. A possible strategy would be to have the errors written to a file and to then have a few lines in your .login script like; if ( -f .filter_errors) then echo " " echo "Filter program errors;" cat .filter_errors echo " " endif You can also use the -v flag in combination with the above to have the errors written to a file and a single line indi- cating messages being sent off or saved to folders written to the console by having your .forward file; "|filter -v > /dev/console 2>> $HOME/.filter_errors" Suffice to say, you can get pretty tricky with all this!! One last point - if you're interested in having it beep (for output to the screen, I would think) you can use the -a (audible) flag for any of these invocations! Summarizing the Actions Taken The Filter program keeps a log of all actions performed, including what rules it matched against, in your home direc- tory in a file called .filter_log. You can either directly operate on this file, or, much more recommended, you can one of the two summarize flags to the program and let it do the work for you! The difference between the two is best demonstrated by exam- ple; % filter -s Summary of filter activity; The default rule of putting mail into your mailbox was used 18 times Rule #3: (save in "/users/taylor/Mail/culture") was applied 2 times. vs % filter -S Mail from root about PUT in mailbox: the default action Mail from taylor about Filter Summary PUT in mailbox: the default action Mail from hpcea!hpcesea!hpcesed!scott@hplabs.HP.COM about Comments and questions about elm PUT in mailbox: the default action [etc etc] To actually use either of the summarizing options, there are two ways that are recommended; The preferred way is to have a line in either your crontab (ask your administrator for help with this) that invokes the filter program as often as you desire with the -s flag. For example, I have a summary mailed to me every morning at 8:00 am; 0 8 * * * "/usr/local/bin/filter -s | elm -s 'Filter Summary' taylor" An alternative is to have your .login execute the command each time. Note that each time the summary is generated your log file is cleared out, so if you want to keep a long list of actions performed you'll need to save it as you display it. A way to do this would be, if you were to have the invoca- tion in your .login script, to use; echo "Filter Log;" filter -s | tee -a PERM.filter.log which would append a copy of all the output to the file `PERM.filter.log'. Further Testing of the Ruleset With the readmsg command available, it is quite easy to test the rules you've written to see if they'll do what you desire. For example, we can use the -n flag to filter, which means `don't actually do this, just tell me what rule you matched, if any, and what action you would have performed' (you can see why a single letter flag is easier to type in!!), and feed it each message in our mailbox by using a command like; % set message=1 % set total_messages=`messages` % while (1) > if ($message > $total_messages) exit > echo processing message $message > readmsg -h $message | filter -n > echo " " > @ messages++ > end which will then hand each of the messages in your mailbox to the filter program and display what action would have been taken with that message and why. For example, if we do this for a few interesting messages in my mailbox, we'd end up with output like; Mail from taylor about filter test FORWARDED to hpldat!taylor by rule; subject="filter test" ? forward "hpldat!taylor" Mail from bradley%hplkab@hplabsc about Re: AI-ED mailing address for HP PUT in mailbox: the default action Mail from taylor about display-to-console EXECUTED "cat - > /dev/console" (sharp users will notice that this is exactly the same for- mat as the longer summary listing!!) What Forwarded Messages Look Like When a message is forwarded to another user by the action being specified as ``forward address'', then the program can generate one of two styles of message. If the message is to you, then it'll simply add it to your mailbox in such a way as to ensure that the return address is that of the person who sent the message and so on. If not, then the message is enclosed in a message of the form; From taylor Thu Oct 2 15:07:04 1986 Date: Thu, 2 Oct 86 15:06:58 pdt Subject: "filter test" From: The filter of taylor@hpldat <taylor> To: hpldat!taylor X-Filtered-By: filter, version 1.4 -- Begin filtered message -- From taylor Thu Oct 2 15:06:41 1986 Date: Thu, 2 Oct 86 15:06:33 pdt From: Dave Taylor <taylor> Subject: filter test Just a simple test. -- End of filtered message -- The subject of the actual message is the same as the subject of the message being forwarded, but in quotes. The `From:' field indicates how the message was sent, and the `X- Filtered-By:' identifies what version of filter is being used. Areas to Improve While the filter program as presented herein is obviously a nice addition to the set of tools available for dealing with electronic mail, there are some key features that are miss- ing and will be added in the future based on demand. As I see it, the main things missing are; 1. The ability to use regular expressions in the pat- terns. This would be a very nice feature! 2. Perhaps more actions available (but what?) 3. Certainly the ability to filter based on any field or combination of fields. Warnings and Things to Look Out For Since this is a pretty simple program, there are a few pit- falls, some of which have already been mentioned; Order counts in the rules. Beware! Matching is pretty simple - make sure your patterns are suf- ficiently exclusive before having any destructive rules. Finally, as with the rest of the Elm mail system, I welcome feedback and suggestion on how to improve this program!!