Networks under my control (and more so some I've been called in to assist) are currently under attack by SMTP dictionary-attackers, which seems to be reincarnations of the ghosts of GeolistPro. [ scumbags that are trying to deliver spam, and/or are trying to learn every possible email address in a given domain, to the tune of up to 550,000 per attack (there's obviously a lot of usernames@ scraped from existing spam-lists).
It's my belief that some (or all) of this activity is currently instigated by EarthOnline Software, makers of GeoList Pro. This URL is the basis for my suspicions: http://www.earthonline-software.com/targeted-a.html GeoList's "feature" was that it collected regionally targeted lists of e-mail addresses. How can one do that? The only two ways I can think of are dictionary attacks against ISP web servers ( GET /~aaaa) or dictionary attacks against ISP's SMTP servers (RCPT TO: <aaaaa>). The former method would be much less successful, since not all customers will have their own web directories, and not all providers will use the /~ syntax either. Mike P.S. The SMTP abuse listserv is still here: http://www.kopower.com/mailman/listinfo/smtpabuse