Microsoft is rolling out a new feature in its Teams platform that allows users to start chats with anyone using just an email address, even if the recipient is not a Teams user. The update, which begins its targeted release in early November 2025 and is expected worldwide by January 2026, is designed to enhance collaboration with external partners. However, the announcement has triggered notable security concerns among cybersecurity experts. Professionals are warning that the "Chat with Anyone" functionality could become a prime vector for sophisticated phishing campaigns and the distribution of malware. The fear is that attackers could exploit the guest-join mechanism to send fraudulent invitations containing malicious payloads directly into secure corporate chat environments. Microsoft has acknowledged the potential security implications, advising organizations to update their internal documentation.