Spam can deliver phishing links, malware, and fraudulent messages, making it a path for account theft and other cyberattacks.
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Background for this topic.
Spam is unsolicited, usually bulk messaging sent through email, text messages, social platforms, or other communication services. It may be commercial advertising, but security-relevant spam commonly includes deceptive messages designed to look like trusted communications. Automated campaigns can target large numbers of recipients at low cost, while compromised accounts and spoofed sender identities can make messages appear more credible.
Spam is a delivery channel for phishing, malware, fraudulent payment requests, and credential theft; links or attachments should therefore be treated as untrusted until verified. Defenses include reputation and content filtering, user reporting, attachment and URL analysis, and email authentication controls such as SPF, DKIM, and DMARC to reduce sender spoofing. Security teams should preserve relevant message headers and indicators when investigating campaigns, blocking associated infrastructure and checking whether recipients interacted with the content.
Microsoft is investigating an Exchange Online bug causing anti-spam systems to mistakenly quarantine some users' emails. [...]