An HTML webpage or form is a document with name ending with ".html" or ".htm".
Remember, if in doubt or uncertain about an email message, online users should contact the sender via telephone or other means, if possible, to verify the authenticity of the email message.
A Sample of a Malicious HTML or Web Form Email
Wed 12/07/2017 08:20
From: Adeyemi Samuel
Attachment: Letter of Confirmation.html (264 KB)
Please refer to the attached letter. Tried calling on the phone. Was not successful. Let me know what you think.