On Tue, 8 Dec 2009, Michael Holstein wrote:
3. Spammers abusing your webmail and/or remote message submission service using phished credentials.
I'll admit .. this has happened a few times too. Usually we see the incoming phish attempt and configure an outbound block for RE: (same subject) and it never fails .. we catch at least one person that responds. We've seriously considered sending our own phishing emails with a link that automatically disables anyone's account if they click it.
In addition to rate-limiting, you can get some assistance from the anti-phishing email reply blacklist (see http://code.google.com/p/anti-phishing-email-reply/) which is included in the Sanesecurity ClamAV add-on databases (see http://sanesecurity.co.uk/databases.htm). Even if it's too late to block the incoming phish it can be useful to block your users' replies. There's also "Kochi" which analyses email for phishing- related patterns, including detecting messages that contain users' passwords (see http://oss.lboro.ac.uk/kochi1.html). There's a fair amount of discussion of this kind of thing on the hied-emailadmin list (see https://listserv.nd.edu/cgi-bin/wa?A0=HIED-EMAILADMIN).
Our volume is 1.5-2m msg/day, and I'd say we catch ~95% of it .. but when a batch gets through and a third of our students have mail forwarded to Yahoo, from Yahoo's point-of-view, they just got 10,000 spam from our IPs.
Ah, you have rather more forwarding than we do.
Anyone know how to do this in Domino off-hand? (without sending IBM a fat check) .. if so, I'd love to hear about it so I can tell our Lotus admins.
Put a Unix mailer between it and the real world :-) I think Exim's rate limiting facility is excellent, but then I wrote it :-) Tony. -- <fanf@exim.org> <dot@dotat.at> http://dotat.at/ ${sg{\N${sg{\ N\}{([^N]*)(.)(.)(.*)}{\$1\$3\$2\$1\$3\n\$2\$3\$4\$3\n\$3\$2\$4}}\ \N}{([^N]*)(.)(.)(.*)}{\$1\$3\$2\$1\$3\n\$2\$3\$4\$3\n\$3\$2\$4}}