Huhu, On 13-Nov-01 Sven Michels wrote:
Boris Lorenz wrote:
I agree with you to some extend.
My 0.02c: A host with a broken FQDN or no FQDN at all should *not* be allowed to take part in normal smtp traffic. If some admin/provider/whatever is unable to create proper forward and reverse DNS and MX zones/entries for a domain, he/she should go baking cookies for christmas instead, sorry.
thats also my point of view, but if you're in a business, you can't deal this way. Your Customers NEED to contact you. Many of them are not able to configure DNS the right way. So if you block them, you'll never get their money ;)
Agreed! LOL :) [...]
If I would let pass mails with unresolveable/suspicious domains, I would get roughly 50% more spam than with the block. half ack. many spam is delivered over 'good' configurated mailservers WITH fqdn and reverse DNS. You have to deal with it. grep your logs after connections from unknown hosts and look how many legitimate mail is included.
Yep, I create some mail stats on a regular basis (twice a month), and as of now, roughly 3-4% of known-good mails are rejected. Rather a lot. That's why I have to write many "hey-your-MX-sucks" mails... ;)
If I have the time, I usually drop the domain admins a lil' mail, informing them about their DNS problems.
good. that can also be done by a script. the problem is that many domain admins aren't agree with you :( Things like: 'your mailsetup is broken, the sender domain exists and has a/mx records.' are the most used respons ;)
Oh yeah, I have enough of mails like this in my archives... I often found myself in the mids of heated debates about the domain name system with some ppl (admins?), although I don't see any argueable parts in it. Perhaps I should change from Aspirine to Prozac.
I may be anal about this, but thanks to these and other strict precautions, our spam traffic volume is near zero.
Spam filtering is not easy, you need really to figure out how many spam and how many legitimate mail youre blocking. if thats ok for you to block 1-5 good ppl and 10-50 bad ppl, do it :)
Well, I got less than 10% noise in my usual mail traffic (see above), but I agree with you, anti-spam isn't kids play, at least not if you want to tune things finely and not just raise some block-all-and-log walls.
Junk mail is war. RFCs do not apply.
:) Yep. That's why I act against some RFCs and also block mails with empty
sender lines. Which is much fun for recipients of certain, uh,
"leisure-oriented" spare-time list mails (Horoscopes, party tips, news flashes,
erotica, you know the score...).
Boris Lorenz