SpamCop - Cisco's anti-spam service - failed to renew spamcop.net over the weekend, causing it to lapse and resulting in countless messages being falsely labeled and rejected as spam around the world. . From what we can tell, this is what happened. When the domain name expired, *.spamcop.net resolved to a domain parking service's IP address. The way that SpamCop's DNS-based blocking list works is that if you, for example, want to check that an email sent from a system with the IP address 1.2.3.4 is legit, you run a DNS query on 4.3.2.1.bl.spamcop.net. If SpamCop returns a valid DNS entry for that lookup, then it's an IP address known to have sent out spam in the past and should be treated with suspicion. . Recent email communication issues were triggered by the expiration of SpamCop's domain, affecting anti-spam mechanisms globally.. SpamCop Issues, Email Delivery Problems, Domain Expiration Effects. . Brittany Day
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