Yes, Microsoft Outlook is considered secure for sending sensitive files, especially if additional security measures are taken. Outlook offers standard encryption, spam filtering, and malware protection features that can help protect your data. Moreover, Microsoft 365, which includes Outlook, also provides advanced security measures such as advanced threat protection (ATP) that help defend against sophisticated threats hidden in email attachments and links, and can also secure sensitive data with encryption. However, while Outlook is secure, the security can be compromised if the email recipient’s email platform is not secure. Also, the email can be intercepted while in transit or while stored on email servers or on a user’s computer. So, to share sensitive files, it is often recommended to use a secure file sharing platform and share the link through email instead. Always remember to use strong, unique passwords and enable two-factor authentication whenever possible.