| CAccount | A group of associated Mailboxes |
| CAccountEntry | An entry in the Autocrypt account Menu |
| CAddress | An email address |
| CAlias | A shortcut for an email address or addresses |
| CAliasFunction | A NeoMutt function |
| CAliasMenuData | AliasView array wrapper with Pattern information - |
| CAliasView | GUI data wrapping an Alias |
| CAnsiColor | An ANSI escape sequence |
| CAttachCtx | A set of attachments |
| CAttachFunction | A NeoMutt function |
| CAttachMatch | An attachment matching a regex for attachment counter |
| CAttachPrivateData | Private state data for Attachments |
| CAttachPtr | An email to which things will be attached |
| CAttrColor | A curses colour and its attributes |
| CAutocryptAccount | Autocrypt account |
| CAutocryptData | Data to pass to the Autocrypt Functions |
| CAutocryptFunction | A NeoMutt function |
| CAutocryptGossipHistory | Autocrypt gossip history |
| CAutocryptHeader | Parse Autocrypt header info |
| CAutocryptPeer | Autocrypt peer |
| CAutocryptPeerHistory | Autocrypt peer history |
| CB64Context | Cursor for the Base64 conversion |
| CBdbStoreData | Berkeley DB Store |
| CBody | The body of an email |
| CBodyCache | Local cache of email bodies |
| CBrowserFunction | A NeoMutt function |
| CBrowserPrivateData | Private state data for the Browser |
| CBrowserState | State of the file/mailbox browser |
| CBuffer | String manipulation buffer |
| CCertMenuData | Certificate data to use in the Menu |
| CChildCtx | Keep track of the children of an article |
| CCidMap | List of Content-ID to filename mappings |
| CColorElement | One element of a Colour |
| CCommand | |
| CCompareData | Private data for browser_sort_helper() |
| CCompileOptions | List of built-in capabilities |
| CCompleteOps | |
| CCompletionData | State data for auto-completion |
| CComposeAttachData | Data to fill the Compose Attach Window |
| CComposeBarData | Data to fill the Compose Bar Window |
| CComposeFunction | A NeoMutt function |
| CComposeSharedData | Shared Compose Data |
| CCompressInfo | Private data for compress |
| CComprOps | |
| CConfigDef | |
| CConfigSet | Container for lots of config items |
| CConfigSetType | |
| CConfigSubset | A set of inherited config items |
| CConnAccount | Login details for a remote server |
| CConnection | |
| CContent | Info about an attachment |
| CContentState | Info about the body of an email |
| CCryptCache | Internal cache for GPGME |
| CCryptEntry | An entry in the Select-Key menu |
| CCryptKeyInfo | A stored PGP key |
| CCryptModule | A crypto plugin module |
| CCryptModuleSpecs | |
| CCursesColor | Colour in the ncurses palette |
| CDnArray | An X500 Distinguished Name |
| CEmail | The envelope/body of an email |
| CEmailCompare | Context for email_sort_shim() |
| CEmailFormatInfo | Data passed to index_format_str() |
| CEmailGarbageCollector | Email garbage collection |
| CEmailNode | List of Emails |
| CEnrichedState | State of enriched-text parser |
| CEnterFunction | A NeoMutt function |
| CEnterState | Keep our place when entering a string |
| CEnterWindowData | Data to fill the Enter Window |
| CEnumDef | An enumeration |
| CEnvelope | The header of an Email |
| CEnvelopeFunction | A NeoMutt Envelope function |
| CEnvelopeWindowData | Data to fill the Envelope Window |
| CEtags | Enriched text tags |
| CEventAccount | An Event that happened to an Account |
| CEventAlias | An alias-change event |
| CEventBinding | A key binding Event |
| CEventColor | An Event that happened to a Colour |
| CEventConfig | A config-change event |
| CEventEmail | An Event that happened to an Email |
| CEventHeader | An event that happened to a header |
| CEventMailbox | An Event that happened to a Mailbox |
| CEventMview | An Event that happened to an MailboxView |
| CEventWindow | An Event that happened to a Window |
| CExpando | Parsed Expando trees |
| CExpandoDefinition | Definition of a format string |
| CExpandoFormat | Formatting information for an Expando |
| CExpandoNode | Basic Expando Node |
| CExpandoParseError | Buffer for parsing errors |
| CExpandoRenderCallback | |
| CExtkey | Map key names from NeoMutt's style to Curses style |
| CFetchCtx | Keep track when getting data from a server |
| CFgetConv | Cursor for converting a file's encoding |
| CFileCompletionData | Input for the file completion function |
| CFlowedState | State of a Format-Flowed line of text |
| CFolder | A folder/dir in the browser |
| CFolderFile | Browser entry representing a folder/dir |
| CGlobalFunction | A NeoMutt function |
| CGpgmeData | Data to pass to the Gpgme Functions |
| CGpgmeFunction | A NeoMutt function |
| CGroup | A set of email addresses |
| CGroupNode | An element in a GroupList |
| CHashAlgorithm | PGP Hashing algorithm |
| CHashElem | The item stored in a Hash Table |
| CHashKey | The data item stored in a HashElem |
| CHashTable | A Hash Table |
| CHashWalkState | Cursor to iterate through a Hash Table |
| CHCacheEntry | Wrapper for Email retrieved from the header cache |
| CHeaderCache | Header Cache |
| CHelpbarWindowData | Help Bar Window data - |
| CHistory | Saved list of user-entered commands/searches |
| CHistoryData | Data to pass to the History Functions |
| CHistoryEntry | A line in the History menu |
| CHistoryFunction | A NeoMutt function |
| CHook | A list of user hooks |
| CIBarPrivateData | Data to draw the Index Bar |
| CIconvCacheEntry | Cached iconv conversion descriptor |
| CImapAccountData | IMAP-specific Account data - |
| CImapAuth | IMAP authentication multiplexor |
| CImapCommand | IMAP command structure |
| CImapEmailData | IMAP-specific Email data - |
| CImapHeader | IMAP-specific header |
| CImapList | Items in an IMAP browser |
| CImapMboxData | IMAP-specific Mailbox data - |
| CIndexFunction | A NeoMutt function |
| CIndexPrivateData | Private state data for the Index |
| CIndexSharedData | Data shared between Index, Pager and Sidebar |
| CInheritance | An inherited config item |
| CKeyEvent | An event such as a keypress |
| CKeymap | A keyboard mapping |
| CLine | A line of text in the pager |
| CListNode | A List node for strings |
| CLmdbStoreData | LMDB store |
| CLogLine | A Log line |
| CLookup | Regex to String lookup table |
| CLz4ComprData | Private Lz4 Compression Data |
| CMailbox | A mailbox |
| CMailboxNode | List of Mailboxes |
| CMailboxView | View of a Mailbox |
| CMailcapEntry | A mailcap entry |
| CMaildirEmailData | Maildir-specific Email data - |
| CMaildirMboxData | Maildir-specific Mailbox data - |
| CMapping | Mapping between user-readable string and a constant |
| CMboxAccountData | Mbox-specific Account data - |
| CMbTable | Multibyte character table |
| CMd5Ctx | Cursor for the MD5 hashing |
| CMdEmail | A Maildir Email helper |
| CMenu | |
| CMenuFuncOp | Mapping between a function and an operation |
| CMenuFunction | A NeoMutt function |
| CMenuOpSeq | Mapping between an operation and a key sequence |
| CMenuStatusLineData | Data for creating a Menu line |
| CMessage | A local copy of an email |
| CMhEmail | A Mh Email helper |
| CMhMboxData | Mh-specific Mailbox data - |
| CMhSequences | Set of MH sequence numbers |
| CMimeNames | MIME name lookup entry |
| CMonitor | A watch on a file |
| CMonitorInfo | Information about a monitored file |
| CMsgWinWindowData | Message Window private Window data |
| CMUpdate | Store of new offsets, used by mutt_sync_mailbox() |
| CMuttFileIter | State record for mutt_file_iter_line() |
| CMuttThread | An Email conversation |
| CMuttWindow | |
| CMwChar | Description of a single character |
| CMwChunk | A block of characters of one colour |
| CMxOps | |
| CNeoMutt | Container for Accounts, Notifications |
| CNewsrcEntry | An entry in a .newsrc (subscribed newsgroups) |
| CNmAccountData | Notmuch-specific Account data - |
| CNmEmailData | Notmuch-specific Email data - |
| CNmMboxData | Notmuch-specific Mailbox data - |
| CNmTags | Array of Notmuch tags |
| CNntpAcache | NNTP article cache |
| CNntpAccountData | NNTP-specific Account data - |
| CNntpEmailData | NNTP-specific Email data - |
| CNntpMboxData | NNTP-specific Mailbox data - |
| CNodeCondDatePrivate | Private data for a Conditional Date - |
| CNodeExpandoPrivate | Private data for an Expando - |
| CNodePaddingPrivate | Private data for a Padding Node - |
| CNotify | Notification API |
| CNotifyCallback | Data passed to a notification function |
| CObserver | An observer of notifications |
| CObserverNode | List of Observers |
| CPagerData | Data to be displayed by PagerView |
| CPagerFunction | A NeoMutt function |
| CPagerPrivateData | Private state data for the Pager |
| CPagerView | Paged view into some data |
| CParameter | Attribute associated with a MIME part |
| CPattern | A simple (non-regex) pattern |
| CPatternCache | Cache commonly-used patterns |
| CPatternData | Data to pass to the Pattern Functions |
| CPatternEntry | A line in the Pattern Completion menu |
| CPatternFlags | Mapping between user character and internal constant |
| CPatternFunction | A NeoMutt function |
| CPBarPrivateData | Data to draw the Pager Bar |
| CPgpCache | List of cached PGP keys |
| CPgpCommandContext | Data for a PGP command |
| CPgpData | Data to pass to the Pgp Functions |
| CPgpEntry | An entry in a PGP key menu |
| CPgpFunction | A NeoMutt function |
| CPgpKeyInfo | Information about a PGP key |
| CPgpUid | PGP User ID |
| CPopAccountData | POP-specific Account data - |
| CPopAuth | POP authentication multiplexor |
| CPopCache | POP-specific email cache |
| CPopEmailData | POP-specific Email data - |
| CPostponeData | Data to pass to the Postpone Functions |
| CPostponeFunction | A NeoMutt function |
| CPreviewFunction | A message preview function |
| CPreviewWindowData | Data to fill the Preview Window |
| CPrexStorage | A predefined / precompiled regex |
| CProgressWindowData | Progress Bar Window Data |
| CQuoteStyle | Style of quoted text |
| CRangeRegex | Regular expression representing a range |
| CRealKey | Hcache key name (including compression method) |
| CRegex | Cached regular expression |
| CRegexColor | A regular expression and a color to highlight a line |
| CRegexNode | List of regular expressions |
| CReplace | List of regular expressions |
| CRfc2231Parameter | MIME section parameter |
| CRocksDbStoreData | RocksDB store |
| CSaslSockData | SASL authentication API - |
| CSBarPrivateData | Private data for the Simple Bar |
| CSbEntry | Info about folders in the sidebar |
| CScore | Scoring rule for email |
| CSearchState | Holds state of a search |
| CSeqsetIterator | UID Sequence Set Iterator |
| CSidebarData | Data passed to sidebar_format_str() |
| CSidebarFunction | A NeoMutt function |
| CSidebarWindowData | Sidebar private Window data - |
| CSimpleDialogWindows | Tuple for the results of simple_dialog_new() |
| CSlist | String list |
| CSmimeCommandContext | Data for a SIME command |
| CSmimeData | Data to pass to the Smime Functions |
| CSmimeFunction | A NeoMutt function |
| CSmimeKey | An SIME key |
| CSmtpAccountData | Server connection data |
| CSmtpAuth | SMTP authentication multiplexor |
| CState | Keep track when processing files |
| CStoreOps | |
| CSysExits | Lookup table of error messages |
| CTag | LinkedList Tag Element |
| CTextSyntax | Highlighting for a piece of text |
| CThreadsContext | The "current" threading state |
| CTlsSockData | TLS socket data - |
| CTunnelSockData | A network tunnel (pair of sockets) |
| CTz | List of recognised Timezones |
| CUrl | A parsed URL proto://user:password@host:port/path?a=1&b=2 |
| CUrlQuery | Parsed Query String |
| CUserHdrsOverride | Which headers have been overridden |
| CWindowState | The current, or old, state of a Window |
| CZlibComprData | Private Zlib Compression Data |
| CZstdComprData | Private Zstandard Compression Data |
| CZstrmContext | Data compression layer |
| CZstrmDirection | A stream of data being (de-)compressed |
