Zendesk ticket systems hijacked in massive global spam wave

A widespread spam campaign beginning on January 18 abused Zendesk instances' ability to accept unverified support tickets, allowing attackers to generate automated confirmation emails en masse to arbitrary addresses. The resulting high-volume, often alarming messages (without apparent phishing links) affected numerous organizations and bypassed some spam filters; Zendesk and impacted companies have issued guidance and implemented safety features to limit this relay-spam abuse.