mh-invisible-header-fields-compiled

mh-invisible-header-fields-compiled is a variable defined in `mh-e.el'.
Its value is

"^\\(A\\(?:\\(?:buse-Reports-To\\|cc\\(?:ept\\(?:-?Language\\)\\|reditor\\)\\|l\\(?:so-Control\\|ternate-recipient\\)\\|pproved\\(?:-By\\)?\\|rticle-\\(?:\\(?:Nam\\|Updat\\)es\\)\\|ut\\(?:hentication-Results\\|o\\(?:-?forwarded\\)\\)\\):\\)\\|B\\(?:\\(?:estservhost\\|ounces\\(?:\\(?:-T\\|_t\\)o\\)\\|ytes\\):\\)\\|C\\(?:ancel-\\(?:\\(?:Key\\|Lock\\):\\)\\|o\\(?:mment:\\|n\\(?:t\\(?:ent-\\|rol:\\)\\|version\\(?:\\(?:-With-Loss\\)?:\\)\\)\\)\\)\\|D\\(?:KIM-\\|L-Expansion-History:\\|eliver\\(?:\\(?:ed-To\\|y\\(?:-Date\\)?\\):\\)\\|is\\(?:c\\(?:arded-X400-\\|lose-Recipients:\\)\\|\\(?:position-Notification-\\(?:Options\\|To\\)\\|tribution\\):\\)\\|omainKey-\\(?:Signature:\\)?\\)\\|E\\(?:\\(?:n\\(?:coding\\|velope-to\\)\\|rrors-To\\|xpir\\(?:es\\|y-Date\\)\\):\\)\\|F\\(?:ace:\\|o\\(?:\\(?:llowup-To\\|r\\(?:-\\(?:Approval\\|Comment\\|Handling\\)\\|warded\\)\\):\\)\\|rom \\)\\|Generate-Delivery-Report:\\|I\\(?:\\(?:mportance\\|n\\(?:-Reply-To\\|complete-Copy\\)\\):\\)\\|Keywords:\\|L\\(?:anguage:\\|i\\(?:nes:\\|st-\\)\\)\\|M\\(?:ail\\(?:\\(?:-\\(?:Copies-To\\|Followup-To\\|Reply-To\\|from\\)\\|ing-List\\):\\)\\|essage-\\(?:\\(?:Content\\|Id\\|Type\\):\\)\\|ime-Version\\|sgid:\\)\\|NNTP-\\|O\\(?:bsoletes:\\|ld-Return-Path:\\|penPGP:\\|rigina\\(?:l-\\(?:Encoded-Information-Types:\\|Lines:\\|N\\(?:NTP-\\|ewsgroups:\\)\\|Path:\\|Rec\\(?:\\(?:eived\\|ipient\\):\\)\\|To:\\|X-\\)\\|t\\(?:\\(?:ion-Client\\|or\\):\\)\\)\\)\\|P\\(?:1-\\(?:\\(?:Content-Type\\|Message-Id\\|Recipient\\):\\)\\|ath:\\|ics-Label:\\|osted-To:\\|r\\(?:e\\(?:cedence:\\|v\\(?:-Resent\\|ent-NonDelivery-Report:\\)\\)\\|iority:\\)\\)\\|Re\\(?:ad-Receipt-To:\\|ceived\\(?:\\(?:-SPF\\)?:\\)\\|ferences:\\|gistered-Mail-Reply-Requested-By:\\|mailed-\\|pl\\(?:\\(?:aces\\|ied\\):\\)\\|sent-\\|turn-\\(?:\\(?:Path\\|Receipt-\\(?:Requested\\|To\\)\\):\\)\\)\\|S\\(?:\\(?:e\\(?:al-Send-Time\\|e-Also\\|nsitivity\\)\\|peech-Act\\|\\(?:tatu\\|upersede\\)s\\):\\)\\|T\\(?:elefax:\\|hread-\\(?:\\(?:Index\\|Topic\\):\\)?\\|ranslat\\(?:\\(?:ed-By\\|ion-Of\\):\\)\\)\\|Ua-Content-Id:\\|Via:\\|X\\(?:-\\(?:A\\(?:CL-Warn:\\|MAZON\\|OL-IP:\\|buse-\\(?:Info:\\|and-DMCA-\\)\\|\\(?:c\\(?:cept-Language\\|k\\)\\|dmin\\(?:istrivia-To\\)?\\|n\\(?:alysisOut\\|ti\\(?:Abuse\\|virus-Scanner\\)\\)\\|pparently-\\(?:From\\|To\\)\\|ttribution\\|u\\(?:ditID\\|t\\(?:h\\(?:enticat\\(?:ed-\\(?:Info\\|Sender\\)\\|ion-\\(?:Info\\|Warning\\)\\)\\|ority-Analysis\\)\\|o-Response-Suppress\\)\\)\\):\\)\\|B\\(?:FI:\\|PS\\(?:[12]:\\)\\|a\\(?:rracuda-\\|yes-Prob:\\)\\|eenthere:\\|igfish:\\|ogosity:\\|rightmail\\(?:\\(?:-Tracker\\|Filtered\\):\\)\\|ugzilla-\\)\\|C\\(?:a\\(?:m\\(?:-\\|paign\\(?:\\(?:\\(?:-I\\|i\\)d\\)?:\\)\\)\\|nIt-Geo:\\)\\|loudmark-SP-\\|\\(?:o\\(?:m\\(?:ment\\|pl\\(?:aints-To\\|eted\\)\\)\\|n\\(?:firm-Reading-To\\|tent\\(?:-Filtered-By\\|Stamp\\)\\)\\|untry-Chain\\)\\|r\\(?:-\\(?:Hashedpuzzle\\|Puzzleid\\)\\|on-Env\\)\\):\\)\\|D\\(?:CC-\\|H-Virus-\\|MCA\\|e\\(?:clude-\\|dicated:\\|livered\\|stination-ID:\\)\\|o\\(?:\\(?:cGen-Versio\\|mai\\)n:\\)\\)\\|E\\(?:FL-Spamscore:\\|ID:\\|LNK-Trace:\\|M-\\|chelon-Distraction\\|mail-Type-Id:\\|n\\(?:\\(?:igmail-Version\\|velope-\\(?:Date\\|From\\|Sender\\|To\\)\\):\\)\\|v\\(?:\\(?:iteMessageId\\|olution\\):\\)\\|xtLoop\\)\\|F\\(?:B-SS:\\|ace\\(?::\\|book\\)\\|o\\(?:lder:\\|rwarded-\\)\\|rom-Line\\|uHaFi:\\)\\|G\\(?:enerated-By:\\|mail-\\|nus-Mail-Source:\\|oogle-\\(?:Sender-Auth:\\)?\\|reylist:\\)\\|H\\(?:PL-\\|R-\\|TTP-UserAgent:\\|a\\(?:beas-\\|shcash:\\)\\|eaders-End:\\|z\\)\\|I\\(?:EEE-UCE-\\|MAP:\\|SI-4-30-3-MailScanner:\\|dentity:\\|mage-URL:\\|nfo:\\|ronPort-\\)\\|J\\(?:2-\\|ira-Fingerprint:\\|un\\(?:\\(?:kmail\\|o\\)-\\)\\)\\|Key:\\|L\\(?:aunchpad-\\|ist\\(?:-\\(?:\\(?:Host\\|\\(?:S\\|Uns\\)ubscribe\\):\\)\\|processor-\\|server:\\)\\|\\(?:oop\\|rde-Mailscanner\\|umos-SenderID\\):\\)\\|M\\(?:AIL-INFO:\\|B-Message-\\|D\\(?:\\(?:RemoteIP\\|aemon-Deliver-To\\):\\)\\|E-Bayesian:\\|HE-Checksum:\\|IME\\(?:\\(?:-Autoconverted\\|OLE\\|Track\\):\\)\\|S\\(?:-\\|Mail-Priority\\)\\|XL-Hash:\\|a\\(?:il\\(?:-from:\\|FlowPolicy:\\|Scanner\\|er_\\|ing\\(?:\\(?:-List\\|ID\\):\\)\\|man-\\(?:\\(?:Approved-At\\|Version\\):\\)\\|utils-Message-Id\\)\\|\\(?:jordomo\\|tch\\|xCode-Template\\):\\)\\|essage\\(?:-\\(?:Id\\|Type:\\)\\|Wall-Score:\\)\\|ms-\\|ozilla-Status:\\|smail-\\)\\|N\\(?:AI-Spam-\\|ews\\(?:\\(?:reader\\)?:\\)\\|o\\(?:-Archive:\\|t\\(?:es-Item:\\|ification\\(?:-\\|s:\\)\\)\\)\\)\\|O\\(?:\\(?:RBL\\|peratingSystem\\|r\\(?:acle-Calendar\\|cl-Content-Type\\|ganization\\|igina\\(?:l\\(?:-\\(?:Arrival-Type\\|Complaints-To\\|Date\\|T\\(?:o\\|race\\)\\)\\|ArrivalTime\\)\\|ting-\\(?:Email\\|IP\\)\\)\\)\\):\\)\\|P\\(?:GP:\\|ID:\\|M\\(?:G-\\|X-Version:\\)\\|STN-\\|o\\(?:\\(?:licyd-Weight\\|stfilter\\):\\)\\|r\\(?:iority:\\|o\\(?:ofpoint-\\|vags-ID:\\)\\)\\)\\|Qotd-\\|R\\(?:CPT-TO:\\|IM-\\|M\\|e\\(?:ceived\\(?:\\(?:-Date\\)?:\\)\\|port-Abuse-To:\\|quest-\\|\\(?:solved-to\\|turn-Path-Hint\\):\\)\\|o\\(?:cketYMMF:\\|ving-\\)\\)\\|S\\(?:A-Exim-\\|B\\(?:\\(?:Class\\|Note\\|Pass\\|R\\(?:S\\|ule\\)\\):\\)\\|FDC-\\|M\\(?:FBL:\\|HeaderMap:\\|TP-\\)\\|PF-\\|asl-enc:\\|canned-By:\\|e\\(?:\\(?:nder\\(?:-ID\\|group\\)?\\|rv\\(?:er-\\(?:Date\\|Uuid\\)\\|ice-Code\\)\\):\\)\\|ieve:\\|ource\\|pam\\(?:Bouncer:\\|[:-]\\)\\|tatus\\|u\\(?:\\(?:bmission\\(?:-Address\\|s-To\\)\\|n-Charset\\):\\)\\)\\|T\\(?:M-IMSS-Message-ID:\\|elecom-Digest\\|race:\\)\\|U\\(?:ID\\(?:L:\\)?\\|NTD-\\|R\\(?:[IL]:\\)\\|SANET-\\|nity\\|se\\(?:net-Provider\\|rInfo1:\\)\\)\\|V\\(?:GI-OESCD:\\|SMLoop:\\|ir\\(?:tualServer\\(?:\\(?:Group\\)?:\\)\\|us-\\)\\|ms-To:\\)\\|W\\(?:\\(?:ebTV-Signature\\|ss-Id\\):\\)\\|X\\(?:-Sender:\\|PT-XSL-Name:\\|WALL-\\)\\|Y\\(?:-GMX-Trusted:\\|Mail-\\|ahoo\\(?:-Newman-\\)?\\)\\|ZixNet:\\|detected-operating-system:\\|eGroups-\\|fmx-\\|mail_abuse_inquiries:\\|\\(?:pair\\|xsi\\)-\\)\\|400-\\|ref:\\)\\)"

Documentation:
*Regexp matching lines in a message header that are not to be shown.
Do not alter this variable directly. Instead, customize
`mh-invisible-header-fields-default' checking for fields normally
hidden that you wish to display, and add extra entries to hide in
`mh-invisible-header-fields'.