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[Asrg] Cutting down spam load

2003-06-19 22:37:32
The notion of outlawing MIME, Base64, HTML, etc among consenting MTAs
and MUAs is red herring.  No one can seriously propose eliminating them.

However, you would cut down you spam load significantly if you rejected
all mail with "Content-type: text/html" SMTP or MIME entity headers
from strangers.  24672 or 73% of the 33807 spam in my 39 day rolling
log of what has been sent toward my traps and filters has that mark.
(It should be 40 days, but I had an attack of bad hands and eyes
this morning.)

It's actually even better than that... since the spam which is HTML-burdened is 
[each] usually 3-5x (or MORE, oftentimes) bigger than spam which isn't.  So 
you'd block (in this case) 73% of the spam MESSAGES but probably 90% or more of 
spam BYTES by this *simple*, easily implemented strategy.

If you have good enough log statistics, check to see what percentage of spam 
BYTES would actually be blocked by taking out messages containing text/html 
message type indications in entity headers.  It would also be interesting to 
see 
how many spams (and percentages of overall spam BYTES) contain attachments 
(message text as JPG/GIF images, or (not used so often recently) .DOC files or 
whatever.  My approach would end up truncating the great majority of those, too.

AND, don't forget, another big benefit is blocking NOT ONLY JUST spam, but also 
viruses/worms/trojans.  In many cases, those are sent from 'legitimate' senders 
and without hijacking open relays... so things like spf wouldn't help (even IF 
you could realistically speaking block 'non-verifiable' senders, which is way 
less than clear) but my permissions-list approach would block probably 80-90% 
or 
more of such malicious stuff, too.  By blocking (by default) ALL attachments 
coming from people you don't normally expect to get attachments from, you're 
blocking malicious code, too.  Sure, you'll open up the "attachments allowed" 
window for people you trust and authorize to send those, but that's going to 
typically be a small percentage of the people you'd normally maybe receive 
(ordinary) E-mails from.

Gordon Peterson                  http://personal.terabites.com/
1977-2002  Twenty-fifth anniversary year of Local Area Networking!
Support the Anti-SPAM Amendment!  Join at http://www.cauce.org/
12/19/98: Partisan Republicans scornfully ignore the voters they "represent".
12/09/00: the date the Republican Party took down democracy in America.



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