In e-mail terminology, unsolicited bulk messages sent to many users, usually for advertising or malicious purposes, are commonly known as ________.

Introduction / Context:
Email has become a standard communication tool, but it is also frequently abused by senders who distribute unwanted messages to large numbers of recipients. These messages can be advertisements, scams or malicious links. In Internet terminology, such unsolicited bulk email has a specific name that appears widely in both technical and everyday usage. This question asks you to recall that term from the list of options provided.

Given Data / Assumptions:

• The emails are unsolicited, meaning the recipients did not request them.
• The messages are often sent in bulk to many users at once.
• They are commonly used for advertising, phishing or spreading malware.
• Options include words like newsgroup, Usenet, backbone and spam.

Concept / Approach:
The established term for unsolicited bulk email is spam. The word originally came from a comedy sketch and later became associated with repetitive or unwanted messages. Today, spam refers to unwanted, often commercial or fraudulent email sent to large lists of addresses. Newsgroups and Usenet are names for early Internet discussion forums where users post messages intentionally. Backbone refers to the main data routes across large networks. Cookies are small pieces of data stored in a browser, not emails. Therefore, spam is the only option that accurately describes unsolicited email in the way the question intends.

Step-by-Step Solution:

Verification / Alternative check:
Email provider interfaces often include a Spam or Junk folder, where unwanted messages are automatically filtered. Anti spam software products describe their function as blocking spam emails and protecting users from unsolicited messages. Internet safety guides advise users on how to avoid spam and phishing attempts, using this term consistently. None of these resources use newsgroup, Usenet, backbone or cookies as the standard name for unwanted email. This wide and consistent usage confirms that spam is the correct answer in this context.

Why Other Options Are Wrong:

• Newsgroup posts: Messages posted to a newsgroup are usually public and topic based; they are not necessarily unsolicited emails.
• Usenet messages: Usenet is a distributed discussion system; messages are posted intentionally as part of forums, not primarily as unwanted email.
• Backbone traffic: Refers to data flowing through major network links, not a type of email.
• Cookies: Small pieces of data stored in a user’s web browser to remember preferences; unrelated to email spam.

Common Pitfalls:
Some learners may confuse spam with viruses or malware and think that spam refers only to malicious attachments. While spam can contain harmful links or files, the defining feature is that it is unsolicited and often mass distributed. Another confusion is between spam and junk in everyday speech; many email providers use both words, but spam is the technical term that appears in exam questions. Remembering that spam equals unwanted email messages will help you quickly select the correct option in similar questions.

Final Answer:
Unsolicited bulk email messages are commonly known as Spam.