gnus-ignored-headers

gnus-ignored-headers is a variable defined in `gnus-art.el'.
Its value is

("^Path:" "^Expires:" "^Date-Received:" "^References:" "^Xref:" "^Lines:" "^Relay-Version:" "^Message-ID:" "^Approved:" "^Sender:" "^Received:" "^X-UIDL:" "^MIME-Version:" "^Return-Path:" "^In-Reply-To:" "^Content-Type:" "^Content-Transfer-Encoding:" "^X-WebTV-Signature:" "^X-MimeOLE:" "^X-MSMail-Priority:" "^X-Priority:" "^X-Loop:" "^X-Authentication-Warning:" "^X-MIME-Autoconverted:" "^X-Face:" "^X-Attribution:" "^X-Originating-IP:" "^Delivered-To:" "^NNTP-[-A-Za-z]+:" "^Distribution:" "^X-no-archive:" "^X-Trace:" "^X-Complaints-To:" "^X-NNTP-Posting-Host:" "^X-Orig.*:" "^Abuse-Reports-To:" "^Cache-Post-Path:" "^X-Article-Creation-Date:" "^X-Poster:" "^X-Mail2News-Path:" "^X-Server-Date:" "^X-Cache:" "^Originator:" "^X-Problems-To:" "^X-Auth-User:" "^X-Post-Time:" "^X-Admin:" "^X-UID:" "^Resent-[-A-Za-z]+:" "^X-Mailing-List:" "^Precedence:" "^Original-[-A-Za-z]+:" "^X-filename:" "^X-Orcpt:" "^Old-Received:" "^X-Pgp:" "^X-Auth:" "^X-From-Line:" "^X-Gnus-Article-Number:" "^X-Majordomo:" "^X-Url:" "^X-Sender:" "^MBOX-Line:" "^Priority:" "^X400-[-A-Za-z]+:" "^Status:" "^X-Gnus-Mail-Source:" "^Cancel-Lock:" "^X-FTN:" "^X-EXP32-SerialNo:" "^Encoding:" "^Importance:" "^Autoforwarded:" "^Original-Encoded-Information-Types:" "^X-Ya-Pop3:" "^X-Face-Version:" "^X-Vms-To:" "^X-ML-NAME:" "^X-ML-COUNT:" "^Mailing-List:" "^X-finfo:" "^X-md5sum:" "^X-md5sum-Origin:" "^X-Sun-Charset:" "^X-Accept-Language:" "^X-Envelope-Sender:" "^List-[A-Za-z]+:" "^X-Listprocessor-Version:" "^X-Received:" "^X-Distribute:" "^X-Sequence:" "^X-Juno-Line-Breaks:" "^X-Notes-Item:" "^X-MS-TNEF-Correlator:" "^x-uunet-gateway:" "^X-Received:" "^Content-length:" "^X-precedence:" "^X-Authenticated-User:" "^X-Comment:" "^X-Report:" "^X-Abuse-Info:" "^X-HTTP-Proxy:" "^X-Mydeja-Info:" "^X-Copyright:" "^X-No-Markup:" "^X-Abuse-Info:" "^X-From_:" "^X-Accept-Language:" "^Errors-To:" "^X-BeenThere:" "^X-Mailman-Version:" "^List-Help:" "^List-Post:" "^List-Subscribe:" "^List-Id:" "^List-Unsubscribe:" "^List-Archive:" "^X-Content-length:" "^X-Posting-Agent:" "^Original-Received:" "^X-Request-PGP:" "^X-Fingerprint:" "^X-WRIEnvto:" "^X-WRIEnvfrom:" "^X-Virus-Scanned:" "^X-Delivery-Agent:" "^Posted-Date:" "^X-Gateway:" "^X-Local-Origin:" "^X-Local-Destination:" "^X-UserInfo1:" "^X-Received-Date:" "^X-Hashcash:" "^Face:" "^X-DMCA-Notifications:" "^X-Abuse-and-DMCA-Info:" "^X-Postfilter:" "^X-Gpg-.*:" "^X-Disclaimer:" "^Envelope-To:" "^X-Spam-Score:" "^System-Type:" "^X-Injected-Via-Gmane:" "^X-Gmane-NNTP-Posting-Host:" "^Jabber-ID:" "^Archived-At:" "^Envelope-Sender:" "^Envelope-Recipients:")

Documentation:
*All headers that start with this regexp will be hidden.
This variable can also be a list of regexps of headers to be ignored.
If `gnus-visible-headers' is non-nil, this variable will be ignored.

You can customize this variable.