Header Category

Header Name

Description

Mandatory
Headers

From:

The e-mail address of the user sending the message, as for e-mail.

Date:

The date and time that the message was originally posted to Usenet. This is usually the date/time that the user submitted the article to his or her local NNTP server.

Newsgroups:

Indicates the newsgroup or set of newsgroups to which the message is being posted. Multiple newsgroups are specified by separating them with a comma; for example: “Newsgroups: news.onegroup,rec.secondgroup”.

Subject:

Describes the subject or topic of the message. Note that this header is mandatory on Usenet despite being optional for e-mail; it is important because it is used by readers to decide what messages to open.

Message-ID:

Provides a unique code for identifying a message; normally generated when a message is sent. The message ID is very important in Usenet, arguably more so than in e-mail. The reason is that delivery of e-mail is performed based on recipient e-mail addresses, while the propagation of Usenet messages is controlled using the message ID header.

Path:

This is an informational field that shows the path of servers that a particular copy of a message followed to get to the server where it is being read. Each time a server forwards a Usenet article, it adds its own name to the list in the Path header. The entries are usually separated by exclamation points.

For example, if a user on Usenet server A posts a message, and it is transported from A to G, then X, then F and finally to the server Q where a second user reads it, the person on server Q would see something like this in the Path header: “Q!F!X!G!A”.

Optional
Headers
(part 1 of 2)

Reply-To:

It is possible to reply back to a Usenet article author using e-mail, which by default goes to the address in the From: line. If this header is present, the address it contains is used instead of the default From: address.

Sender:

This header indicates the e-mail address of the user who is sending the message, if different from the message originator. This is functionally the same as the Sender: header in e-mail messages, but is used in a slightly different way. Normally, when a Usenet message is posted, the sender's e-mail address is automatically filled in to the From: line. If the user manually specifies a different From: line, the address from which the message was actually sent is usually included in the Sender: line. This is used to track the true originating point of articles.

Followup-To:

A reply to a Usenet message is usually made back to Usenet itself, and is called a follow-up. By default, a follow-up goes to the newsgroup(s) specified in the original message's Newsgroups: header. However, if the Followup-To: header is included, follow-ups to that message go to the newsgroups specified in the Followup-To: header instead.

This header is sometimes used to “route” replies to a message to a particular group. Note, however, that when a user replies to a message, this field only controls what appears in the new message's Newsgroups: line by default. The user can override the Newsgroups: header manually.

Optional Headers
(part 2 of 2)

Expires:

All Usenet messages are maintained on each server for only a certain period of time, due to storage limitations. The expiration interval for each newsgroup is controlled by the administrator of each site. If present, this line requests a different expiration for a particular message; it is usually used only for special articles. For example, if a weekly announcement is posted every Monday morning, each article might be set to expire the following Monday morning, to make sure that people see the most current version.

References:

This header lists the message IDs of prior messages in a conversation. For example, if someone posts a question to a newsgroup with message ID “AA207”, and a reply to that message is made, the software will automatically insert the line “References: AA207” into the reply. This is used by software to group together articles into conversations (called threads) to make it easier to follow discussions on busy newsgroups.

Control:

Indicates that the article is a control message and specifies a control action to be performed, such as creating a new newsgroup.

Distribution:

By default, most messages are propagated on Usenet worldwide. If specified, this line restricts the distribution of a message to a smaller area, either geographical or organizational.

Organization:

Describes the organization to which the article sender belongs. Often filled in automatically with the name of the user’s Internet Service Provider.

Keywords:

Contains a list of comma-separated keywords that may be of use to the readers of the message. Keywords can be useful when searching for messages on a particular subject matter. This header is not often used.

Summary:

A short summary of the message; again, rarely used in practice.

Approved:

This header is added by the moderator of a moderated newsgroup to tell the Usenet software that the message has been approved for posting.

Lines:

A count of the number of lines in the message.

Xref:

While Usenet articles are identified by message ID, they are also given a number by each Usenet server as they are received. These article numbers, which differ from one system to the next, are usually listed in this cross-reference header.

This information is used when a message is cross-posted to multiple groups. In that case, as soon as a user reads the message in one group, it is marked as having been read in all the others where it was posted. This way, if the user later reads one of those other groups, they will not see the message again.