Securing your mailing list data is of paramount importance, especially when handling sensitive or personal information. Ensure your Excel and Word files are stored in a secure, password-protected directory on your computer or network. Consider using file encryption for an additional layer of security. Implement strong, unique passwords, and enable two-factor authentication if your files are stored in a cloud-based service. Regularly update your cybersecurity software to protect against malware and unauthorized access. Limit access rights to the files to only those individuals who need them for their tasks, and make sure to educate them on the importance of data privacy and security protocols.