[thelist] sending mail to /dev/null

[Alex Beston]

Hi evolt

how you all had a good xmas.

ok well back to the daily grind

I did a little sum this morning and was quite surprised to see that I 
have a yearly handicap of 100,000 spam messages each year. I cant see it 
getting any less.

So what im thinking doing is running some background daemon process 
which will activate when mail is received and if it doesnt fit one of 
the following criteria [1] it will just trash it. Only trouble is 
ofcourse, I have no idea where to start!

so effectively its the same base functionality as sendmail - ie has to 
be able to activate on the relevant port number for mail receiving 
packets. The program would get first shout at the port but I think 
sendmail would be quite surprised to see the mailbox with mail that it 
hadnt deposited there! Effectively I would be removing sendmails 
collecting facility. Exim would be good but apparently this will be set 
up for me.

Anyway.

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What Im looking for is a filter which stands in front of the mail 
program and removes from the mail stream, mails with bad IP's, and mails 
not on a white list and mail, and any mail that follow ideas of what 
spam can be.

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Not quite sure what to do if a genuine mail comes in from someone who 
has used an unrecognised addressee / username / other to my domain. ie 
if they miss spell my name - like alix at delta.co.uk. Definately want to 
ditch catch-all accounts on my server but I then have the CPU cost of 
sending out bounce messages / unrecognised user type mail - it was a 
good idea in 1996 but not in 2006. So bounce messages then. client 
thinks hes going to get a reply!

Thinking also of adding a disaster recovery layer to the app. have a 
summary of each mail added to a log with the first 255 characters of the 
message kept. perhaps a daily download of a gzip of messages?

Im reckoning that if I implement the above(!) then I could see a nice 
clean mailbox for 2007. yes, it will take that long! so 100,000 more 
spam  to go until that is a reality!

Anyway, if any thoughts on the above, do let me know.
thanks in advance,

best
Alex

[1]

a) fits the white list - ie  is a mail from a subscription list,  is on 
a sent mail list of addressees, is the address book, people ive replyed 
to not in address book etc
b) is not on a ip ban number (the likelyhood of a legit customer coming 
from the same ip as a spammer seems low).  i can create this list from 
the spam i get already and  maybe get some from the public records like 
spamhaus and elsewhere.
c) does not conform to some arbitary rules. one) could be that there 
must be a user-agent in the header for non-subscription mail. two) 
another that someone sending me attachments (usually a spotty script 
kiddy with grudge against the world) that isnt in a) above is to get 
that attachment removed. at least that way i see what a potential 
customer has written to me and i can ask for the message with some 
apology that the current environment of the web neccesitates a removal 
of attachments if the sender is unknown. if s/he doesnt get it, probably 
good to killfile / dev/null  this kkind of mail anyway. three) anything 
with MIME data - i might have that wrong but if i havent subscribed why 
should i pay to have images / MIME data forced upon me? four) too many 
non sensical words. I dont know about you, but most if not all requests 
for quotes for work / initial client  contact is usually well formed.. 
but then again there will always be someone with alot of money to spend 
who can only spell phonetically!

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