spam avoidance (was Re: cpu speed problem)
Tim
ignored_mailbox at yahoo.com.au
Mon Jul 30 10:55:29 UTC 2007
On Mon, 2007-07-30 at 11:25 +0100, Andy Green wrote:
> I found this to be really effective for over a year now:
>
> - greylisting (I use gps + sqlite)
I'm not enamoured of greylisting, though that might be down to the poor
implementations of it that've held my mail up for hours, rather than
greylisting in itself.
> - Spamhaus RBL lookup (IPs that are detected by Spamhaus as sending
> spam to their fake emails get blacklisted here)
Do they get false positives added by malicious people? One of my hosts
uses a RBL system, but I don't think it's spamhaus.
> - tight rules on postfix:
>
> - insist that the server has reverse DNS
Not all do, nor do they really have to, even if it's a damn good idea.
This could be a problem.
> - insist that the recipient user actually exists (end of most
> virus mails)
Does it also reject if the message has more than one recipient, and
they're not all real users?
I put a bait address into a HTML comment on my website, anything that
spammed that (along with any other address) got trashed. No real user
would have seen the bait, but HTML trawlers would. I could kill that
mail with 100% certainty.
--
[tim at bigblack ~]$ uname -ipr
2.6.22.1-33.fc7 i686 i386
Using FC 4, 5, 6 & 7, plus CentOS 5. Today, it's FC7.
Don't send private replies to my address, the mailbox is ignored.
I read messages from the public lists.
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