Message Headers2024-02-13Permanent Message Header Field NamesExpert ReviewGraham Klyne specified that no new header fields be registered that begin with "Downgraded-".
That restriction is now lifted, per .HTTP field name registrations have been moved to
per .
Accept-LanguagemailAlso-ControlnetnewsobsoletedAlternate-RecipientmailApprovednetnewsstandardARC-Authentication-ResultsmailexperimentalARC-Message-SignaturemailexperimentalARC-SealmailexperimentalArchivenetnewsstandardArchived-AtmailstandardArchived-AtnetnewsstandardArticle-NamesnetnewsobsoletedArticle-UpdatesnetnewsobsoletedAuthentication-ResultsmailstandardAuto-SubmittedmailstandardRFC3834 section 5AutoforwardedmailAutosubmittedmailBaseMIMEobsoletedRFC2068 Section 14.11BccmailstandardBodynonereservedCancel-KeynetnewsstandardCancel-LocknetnewsstandardCcmailstandardCommentsmailstandardCommentsnetnewsstandardContent-AlternativeMIMEContent-BaseMIMEobsoletedContent-DescriptionMIMEContent-DispositionMIMEContent-DurationMIMEContent-featuresMIMEContent-IDMIMEContent-IdentifiermailContent-LanguageMIMEContent-LocationMIMEContent-MD5MIMEContent-ReturnmailContent-Transfer-EncodingMIMEContent-Translation-TypeMIMEstandardContent-TypeMIMEControlnetnewsstandardConversionmailConversion-With-LossmailDL-Expansion-HistorymailDatemailstandardDatenetnewsstandardDate-ReceivednetnewsobsoletedDeferred-DeliverymailDelivery-DatemailDiscarded-X400-IPMS-ExtensionsmailDiscarded-X400-MTS-ExtensionsmailDisclose-RecipientsmailDisposition-Notification-OptionsmailDisposition-Notification-TomailDistributionnetnewsstandardDKIM-SignaturemailstandardDowngraded-BccmailobsoletedDowngraded-CcmailobsoletedDowngraded-Disposition-Notification-TomailobsoletedDowngraded-Final-RecipientmailstandardRFC6857 Section 3.1.10Downgraded-FrommailobsoletedRFC6857 Section 3.1.10Downgraded-In-Reply-TomailstandardRFC6857 Section 3.1.10Downgraded-Mail-FrommailobsoletedRFC6857 Section 3.1.10Downgraded-Message-IdmailstandardRFC6857 Section 3.1.10Downgraded-Original-RecipientmailstandardRFC6857 Section 3.1.10Downgraded-Rcpt-TomailobsoletedDowngraded-ReferencesmailstandardRFC6857 Section 3.1.10Downgraded-Reply-TomailobsoletedDowngraded-Resent-BccmailobsoletedDowngraded-Resent-CcmailobsoletedDowngraded-Resent-FrommailobsoletedDowngraded-Resent-Reply-TomailobsoletedDowngraded-Resent-SendermailobsoletedDowngraded-Resent-TomailobsoletedDowngraded-Return-PathmailobsoletedDowngraded-SendermailobsoletedDowngraded-TomailobsoletedEncodingmailEncryptedmailExpiresmailExpiresnetnewsstandardExpiry-DatemailFollowup-TonetnewsstandardFrommailstandardFromnetnewsstandardGenerate-Delivery-ReportmailImportancemailIn-Reply-TomailstandardIncomplete-CopymailInjection-DatenetnewsstandardInjection-InfonetnewsstandardKeywordsmailstandardKeywordsnetnewsstandardLanguagemailLatest-Delivery-TimemailLinesnetnewsdeprecatedList-ArchivemailList-HelpmailList-IDmailList-OwnermailList-PostmailList-Subscribemailperm/list-unsubscribeList-UnsubscribemailList-Unsubscribe-PostmailstandardMessage-ContextmailMessage-IDmailstandardMessage-IDnetnewsstandardMessage-TypemailMIME-VersionMIMEMMHS-Exempted-AddressmailACP123 Appendix A1.1 and Appendix B.105MMHS-Extended-Authorisation-InfomailACP123 Appendix A1.2 and Appendix B.106MMHS-Subject-Indicator-CodesmailACP123 Appendix A1.3 and Appendix B.107MMHS-Handling-InstructionsmailACP123 Appendix A1.4 and Appendix B.108MMHS-Message-InstructionsmailACP123 Appendix A1.5 and Appendix B.109MMHS-Codress-Message-IndicatormailACP123 Appendix A1.6 and Appendix B.110MMHS-Originator-ReferencemailACP123 Appendix A1.7 and Appendix B.111MMHS-Primary-PrecedencemailACP123 Appendix A1.8 and Appendix B.101MMHS-Copy-PrecedencemailACP123 Appendix A1.9 and Appendix B.102MMHS-Message-TypemailACP123 Appendix A1.10 and Appendix B.103MMHS-Other-Recipients-Indicator-TomailACP123 Appendix A1.12 and Appendix B.113MMHS-Other-Recipients-Indicator-CCmailACP123 Appendix A1.12 and Appendix B.113MMHS-Acp127-Message-IdentifiermailACP123 Appendix A1.14 and Appendix B.116MMHS-Originator-PLADmailACP123 Appendix A1.15 and Appendix B.117MT-PrioritymailstandardNewsgroupsnetnewsstandardNNTP-Posting-DatenetnewsobsoletedNNTP-Posting-HostnetnewsobsoletedObsoletesmailOrganizationmailinformationalOrganizationnetnewsstandardOriginal-Encoded-Information-TypesmailOriginal-FrommailstandardOriginal-Message-IDmailperm/original-recipientOriginal-RecipientmailstandardOriginal-SendernetnewsstandardOriginator-Return-AddressmailOriginal-SubjectmailstandardPathnetnewsstandardPICS-LabelmailPosting-VersionnetnewsobsoletedPrevent-NonDelivery-ReportmailPrioritymailReceivedmailstandardReceived-SPFmailstandardReferencesmailstandardReferencesnetnewsstandardRelay-VersionnetnewsobsoletedReply-BymailReply-TomailstandardReply-TonetnewsstandardRequire-Recipient-Valid-SincemailstandardResent-BccmailstandardResent-CcmailstandardResent-DatemailstandardResent-FrommailstandardResent-Message-IDmailstandardResent-Reply-TomailobsoletedResent-SendermailstandardResent-TomailstandardReturn-PathmailstandardSee-AlsonetnewsobsoletedSendermailstandardSendernetnewsstandardSensitivitymailSolicitationmailSubjectmailstandardSubjectnetnewsstandardSummarynetnewsstandardSupersedesmailSupersedesnetnewsstandardTLS-Report-DomainmailstandardTLS-Report-SubmittermailstandardTLS-RequiredmailstandardTomailstandardUser-AgentnetnewsstandardVBR-InfomailstandardX400-Content-IdentifiermailX400-Content-ReturnmailX400-Content-TypemailX400-MTS-IdentifiermailX400-OriginatormailX400-ReceivedmailX400-RecipientsmailX400-TracemailXrefnetnewsstandardProvisional Message Header Field NamesExpert ReviewGraham KlyneRegistration of a Provisional Message Header Field does not of itself imply any kind of
endorsement by the IETF, IANA or any other body.HTTP field name registrations have been moved to
per .
prov/apparently-toApparently-TomailAuthormailCFBL-AddressmailCFBL-Feedback-IDmailDelivered-TomailEDIINT-FeaturesmailEesst-Versionmailprov/errors-toErrors-TomailForm-Submailprov/jabber-idJabber-IDmailprov/jabber-idJabber-IDnetnewsMMHS-Authorizing-UsersmailPriviconmailSIO-LabelmailSIO-Label-Historymailprov/wrong-recipientWrong-Recipientmailprov/x-archived-atX-Archived-Atmaildeprecatedprov/x-archived-atX-Archived-AtnetnewsdeprecatedX-Mittentemailprov/x-pgp-sigX-PGP-SignetnewsX-RicevutamailX-Riferimento-Message-IDmailX-TipoRicevutamailX-TrasportomailX-VerificaSicurezzamailContent-Translation-Type Header Field ValuesSpecification RequiredNik TomkinsonoriginalContent in the original languagehumanContent that has been translated by a human translator
or a human has checked and corrected an automated translationautomatedContent that has been translated by an electronic agent
without proofreading or subsequent correction