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Tag Archives: rDNS

Canadian Anti Spam Law (CASL)–a good step, but not the end of spam

On July 1, a new anti-spam law went into effect in Canada that significantly changes how commercial email messaging operates. The most significant feature of the Canadian Anti Spam Law (CASL) is that commercial senders must obtain express permission (i.e. opt-in) in order to continue sending commercial email. (There is a 3 year transition period […]

Email Blacklists and Cloudmark’s Sender Intelligence (CSI)

Return Path Infographic Return Path recently published an infographic guide to public email blacklists.  As the infographic explains “Public email blacklists are lists of IP Addresses and domains that have been reported and listed as “known” sources of spam.” These lists are used by both large email box providers and enterprises to make decisions about […]

2009 Spam Highlights

As the end of the year draws near, we wanted to highlight some of the spam methodology and attacks Cloudmark observed over the past year. Snowshoe/hailstorm attacks: Snowshoe spam is a campaign which is distributed across multiple IP addresses within a /24 netblock (256 IP addresses) and migrates through large portions of a /16 (65,536 […]

Blocked Email Part 1: “Why me?”

Everyone’s had it happen. You forward a joke to a friend or coworker, email a possible new vendor requesting a quote, or send out your daily/weekly/monthly newsletter and, a short time later, you get back that dreaded notification: “Subject: Undelivered Mail Returned to Sender”. Your first reaction is probably indignation. “I’m not a spammer,” you […]

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