Distributed publication
NNTP distributes articles, not mailboxes.
NNTP was designed for network news systems such as Usenet. A reader connects to a news server, selects a newsgroup, discovers article numbers or identifiers, and retrieves the headers or body of selected articles. Articles are organized by group and carry references that help clients build discussion threads.
Unlike SMTP, which relays a message toward mail systems or a mailbox, NNTP exposes a shared article collection. Unlike HTTP, it has explicit commands for group selection, article retrieval, posting, and news-server synchronization.
Reader protocol
An NNTP client navigates a group before fetching an article.
A typical reader session begins with a greeting, optional authentication, and a GROUP command. The client can ask for article ranges with NEWNEWS or retrieve a list of available articles with LISTGROUP. It can then request headers with HEAD, bodies with BODY, or both with ARTICLE.
Commands and responses use numeric status codes and multiline data blocks. A dot-stuffed termination rule lets the server mark the end of a multiline response without confusing a line in the article with the protocol terminator.
GROUP
Selects a newsgroup and reports its available article range.
HEAD
Retrieves article headers without the full body.
BODY
Retrieves the content of a selected article.
ARTICLE
Retrieves headers and body together.
Server-to-server exchange
News servers exchange articles through feeds.
Server-to-server NNTP can use commands such as IHAVE and TAKETHIS to offer or transfer articles, while CHECK can test whether a peer already has an article identified by its Message-ID. A server decides which groups and articles to accept or forward according to its feed configuration.
The Path header records servers an article has traversed, helping peers avoid loops. A globally unique Message-ID lets servers recognize the same article even when local article numbers differ. This is a distribution model, not a single central database.
Read the message structure
An NNTP article combines Internet-style headers with a news context.
Articles use header fields such as Message-ID, Newsgroups, Subject, From, Date, References, and Path. The Newsgroups field identifies destinations, while References connects replies to earlier articles and supports threading.
The protocol carries article text, not an automatic guarantee of authorship, truth, permanence, or end-to-end confidentiality. Moderation, retention, cancel control messages, server policy, and client behavior affect what readers actually see.
Message-ID
Identifies an article across servers and replication paths.
Newsgroups
Names one or more discussion groups for the article.
References
Links a reply to earlier articles for thread reconstruction.
Path
Records traversed news servers and helps prevent feed loops.
Security and transport
Plain NNTP and NNTPS make different transport promises.
Classic NNTP commonly uses TCP port 119. A client may authenticate with commands such as AUTHINFO USER and AUTHINFO PASS, but authentication alone does not encrypt the session. Without TLS, article content and credentials may be observed or modified on the path.
NNTPS commonly uses implicit TLS on TCP port 563, while STARTTLS can upgrade a plain NNTP connection when the server supports it. The client must still validate the server certificate and trust the server's handling of stored or forwarded content.
Mini investigation
Inspect a news session
Select the strongest clue and identify the next check.
The article may have expired, the group range may differ, or the server may not carry that feed.
Check GROUP ranges, retention, Message-ID availability, and feed policy.
Knowledge check
Test your NNTP model
Answer eight questions.