: Although .txt files are generally safe plain-text documents, attackers often use "double extensions" (e.g., hq_yahoo.txt.exe ) to hide malicious executable code.
: Verify if the email address is actually from an @yahoo.com or @ymail.com domain. Even then, be cautious as sender addresses can be spoofed.
: Avoid opening or downloading any unexpected attachments. Yahoo's official security notices state they will never ask you to download an attachment to resolve an account issue.
: If you did not request this file, it is safest to delete the message and block the sender.
