X-No-Archive is a newsgroup message header used to prevent a Usenet message from being archived in various servers, especially Google.

It was designed to follow the standard message header protocol used in existing newsgroups. In addition to the standard message header lines used in all newsgroup messages (including Path:, From:, Subject:, and Date:), news reader software includes the option for a user to add additional, optional headers to messages. These additional headers are prefixed with the label X- so that they can be ignored by news servers and newsreaders. Thus, the phrase "No Archive" was coined as a way to state "Do not archive this message," and the X- header was added to complete the term X-No-Archive.

The proper header for X-No-Archive is to insert the header into a message as follows:

X-No-Archive: Yes

Some software systems also do not archive if the first line in the body of the message contains that text. This is useful for those users who cannot change the headers of messages they send out.

Use of X-No-Archive began when DejaNews debuted in early 1995. DejaNews was the first large-scale, commercial attempt to archive the entire Usenet news feed (or at least a large part of it), and a number of regular newsgroup participants were concerned about privacy rights, as well as the possibility that their messages could be re-posted through DejaNews at some point in the future. DejaNews addressed these concerns by announcing that it would not archive any Usenet messages containing the X-No-Archive header.

When DejaNews was purchased by Google, Google continued to honor the X-No-Archive protocol. Other newsgroup archiving services have also followed in DejaNews' footsteps, though the decision to archive X-No-Archive messages has been entirely voluntary.

Many popular newsreader and posting software programs, such as Forté Agent, include a standard option to insert X-No-Archive headers into any or all messages at the user's request.