--- /dev/null
+#+TEXINFO_CLASS: info
+#+TEXINFO_HEADER: @syncodeindex pg cp
+#+TITLE: Gnorb Manual
+#+SUBTITLE: for version 1, updated 3 October, 2014
+#+TEXINFO_DIR_CATEGORY: Emacs
+#+TEXINFO_DIR_TITLE: Gnorb: (gnorb)
+#+TEXINFO_DIR_DESC: Glue code for Gnus, Org, and BBDB
+#+OPTIONS: *:nil num:t toc:nil
+* Introduction
+
+Gnorb provides glue code between the Gnus, Org, and BBDB packages.
+It's aimed at supporting email-based project management, and generally
+making it easier to keep track of email communication.
+
+Much of the code consists of single-use convenience functions, but
+tracking email conversations with Org requires is more complicated,
+and requires a bit of setup.
+
+Gnorb can be used in a modular fashion, by selectively loading the
+files "gnorb-org", "gnorb-gnus" or "gnorb-bbdb" instead of plain old
+"gnorb". The package as a whole is rather Org-centric, though, and it
+won't do much of interest without "gnorb-org".
+
+This means that Gnorb doesn't have hard requirements to any of the
+three base libraries. For the libraries you are using, however, you'll
+get best results from using the most recent stable version (yes, that
+means BBDB 3). Some of the features in Gnorb only work with
+development versions of these libraries (those cases are noted below).
+* Installation
+Gnorb is best installed via the Elpa package manager -- look for it in
+`list-packages'.
+
+You can also clone the source code from
+https://github.com/girzel/gnorb, and put the "gnorb" directory on your
+load-path. The Github site is also a good place to report bugs and
+other issues.
+* Setup
+Loading "gnorb" will make the basic functions available. Using Gnorb
+for email tracking takes a bit more setup, however:
+
+1. Email tracking is done via the Gnus registry, so that must be
+ activated with 'gnus-registry-initialize'.
+2. It also requires the org-id package to be loaded, and
+ `org-id-track-globally' set to t (that's the default value, so
+ simply loading the package should be enough).
+3. Add a nngnorb entry to your `gnus-secondary-select-methods'
+ variable. It will look like (nngnorb "Server name"). This does
+ nothing but provide a place to hang nnir searches.
+4. Then put a call to `gnorb-tracking-initialize' in your init files,
+ at some point after the Gnus registry is initialized.
+5. If you're not using a local archive method for saving your sent
+ messages (ie you're using IMAP), you'll also need to tell Gnorb
+ where to find your sent messages. Set the variable
+ `gnorb-gnus-sent-groups' to a list of strings; each string should
+ indicate a fully-qualified group name, eg "nnimap+SERVER:GROUP".
+
+Lastly, Gnorb doesn't bind any keys by default; see the [[id:de1b2579-86c2-4bb1-b77e-3467a3d2b3c7][Suggested
+Keybindings]] section below for possibilities.
+* Email Tracking
+The most interesting thing Gnorb does is using Org headings to track
+email conversations. This can mean anything from reminding yourself to
+write to your mother, to conducting delicate business negotiations
+over email, to running an email-based bug tracker.
+
+Gnorb assists in this process by using the Gnus registry to track
+correspondences between emails and Org headings -- specifically,
+message IDs are associated with Org heading ids. As a conversation
+develops, messages are collected on a heading (and/or its children).
+You can compose new messages directly from the Org heading, and Gnorb
+will automatically associate your sent message with the conversation.
+You can open temporary Gnus *Summary* buffers holding all the messages
+associated with an Org subtree, and reply from there. When you receive
+new messages relevant to a conversation, Gnorb will notice them and
+prompt you to associate them with the appropriate Org heading.
+Attachments on incoming messages can be automatically saved as
+attachments on Org headings, using org-attach.
+
+In general, the goal is to keep track of whole conversations, reduce
+friction when moving between Gnus and Org, and keep you in the Org
+agenda rather than in Gnus.
+** Email-Related Commands
+Email tracking starts in one of three ways:
+
+1. With an Org heading that represents an email TODO. Call
+ `gnorb-org-handle-mail' (see below) on the heading to compose a new
+ message, and start the tracking process.
+2. By calling org-capture on a received message. Any heading captured
+ from a message will automatically be associated with that message.
+3. By calling `gnorb-gnus-outgoing-do-todo' in a message composition
+ buffer -- see below.
+
+There are three main email-related commands:
+
+1. `gnorb-org-handle-mail' is called on an Org heading to compose a
+ new message. By default, this will begin a reply to the most recent
+ message in the conversation. If there are no associated messages to
+ reply to (or you call the function with a double prefix arg), Gnorb
+ will look for mailto: or bbdb: links in the heading, and compose a
+ new message to them.
+
+ The sent message will be associated with the Org heading, and
+ you'll be brought back to the heading and asked to trigger an
+ action on it.
+
+ `gnorb-email-subtree' is an alternative entry-point to
+ `gnorb-org-handle-mail'. It does the same thing as the latter, but
+ first exports the body of the subtree as either text or a file,
+ then inserts the text into the message body, or attaches the file
+ to the message, depending on what you've chosen.
+2. `gnorb-gnus-incoming-do-todo' is called on a message in a Gnus
+ *Summary* buffer. You'll be prompted for an Org heading, taken to
+ that heading, and asked to trigger an action on it.
+3. `gnorb-gnus-outgoing-do-todo' is called in message mode, while
+ composing a new message.
+
+ If called without a prefix arg, a new Org heading will be created
+ after the message is sent, and the sent message associated with it.
+ The new heading will be created as a capture heading, using the
+ template specified by the `gnorb-gnus-new-todo-capture-key' option.
+
+ If you call this function with a prefix arg, you'll be prompted to
+ choose an existing Org heading instead. After the the message is
+ sent, you'll be taken to that heading and prompted to trigger an
+ action on it.
+
+ It's also possible to call this function *after* a message is sent,
+ in case you forgot. Gnorb saves information about the most recently
+ sent message for this purpose.
+
+Because these three commands all express a similar intent, but are
+called in different modes, it can make sense to give each of them the
+same keybinding in the keymaps for Org mode, Gnus summary mode, and
+Message mode, respectively.
+** Trigger Actions
+After calling `gnorb-gnus-incoming-do-todo' on a message, or after
+sending a message associated with an Org heading, you'll be taken to
+the heading and asked to "trigger an action" on it. At the moment
+there are four different possibilities: triggering a TODO state-change
+on the heading, taking a note on the heading (both these options will
+associate the message with the heading), associating the message but
+doing nothing else, and lastly, doing nothing at all.
+
+More actions will be added in the future; it's also possible to
+rearrange or delete existing actions, and add your own: see the
+docstring of `gnorb-org-trigger-actions'.
+** Viewing Tracked Messages in *Summary* Buffers
+:PROPERTIES:
+:END:
+Call `gnorb-org-view' on an Org heading to open an nnir *Summary*
+buffer showing all the messages associated with that heading (this
+requires that you've added an nngnorb server to your Gnus backends). A
+minor mode will be in effect, ensuring that any replies you send to
+messages in this buffer will automatically be associated with the
+original Org heading. You can also invoke
+`gnorb-summary-disassociate-message' ("C-c d") to disassociate the
+message with the Org heading.
+
+As a bonus, it's possible to go into Gnus' *Server* buffer, find the
+line specifying your nngnorb server, and hit "G" (aka
+`gnus-group-make-nnir-group'). At the query prompt, enter an Org-style
+tags-todo Agenda query string (eg "+work-computer", or what have you).
+Gnorb will find all headings matching this query, scan their subtrees
+for gnus links, and then give you a Summary buffer containing all the
+linked messages. This is dog-slow at the moment; it will get faster.
+
+** Hinting in Gnus
+:PROPERTIES:
+:END:
+When you receive new mails that might be relevant to existing Org
+TODOs, Gnorb can alert you to that fact. When
+`gnorb-gnus-hint-relevant-article' is t (the default), Gnorb will
+display a message in the minibuffer when opening potentially relevant
+messages. You can then use `gnorb-gnus-incoming-to-todo' to trigger an
+action on the relevant TODO.
+
+This hinting can happen in the Gnus summary buffer as well. If you use
+the escape indicated by `gnorb-gnus-summary-mark-format-letter" as
+part of your `gnus-summary-line-format', articles that are relevant to
+TODOs will be marked with a special character in the Summary buffer,
+as determined by `gnorb-gnus-summary-mark'. By default, the format
+letter is "g" (meaning it is used as "%ug" in the format line), and
+the mark is "¡".
+** Message Attachments
+:PROPERTIES:
+:END:
+Gnorb simplifies the handling of attachments that you receive in
+emails. When you call `gnorb-gnus-incoming-do-todo' on a message,
+you'll be prompted to re-attach the email's attachments onto the Org
+heading, using the org-attach library.
+
+You can also do this as part of the capture process. Set the
+new :gnus-attachments key to "t" in a capture template that you use on
+mail messages, and you'll be queried to re-attach the message's
+attachments onto the newly-captured heading. Or set
+`gnorb-gnus-capture-always-attach' to "t" to have Gnorb do this for
+all capture templates.
+
+You can also do this using the regular system of MIME commands,
+without invoking the email tracking process. See [[id:de1b2579-86c2-4bb1-b77e-3467a3d2b3c7][Suggested
+Keybindings]], below.
+
+The same process works in reverse: when you send a message from an Org
+heading using `gnorb-org-handle-mail', Gnorb will ask if you want to
+attach the files in the heading's org-attach directory to the outgoing
+message.
+** Likely Workflow
+You receive an email from Jimmy, who wants to rent a room in your
+house. "I'll respond to this later," you think.
+
+You capture an Org TODO from the email, call it "Jimmy renting a
+room", and give it a REPLY keyword. Gnorb quietly records the
+correspondence between the email and the TODO, using the Gnus
+registry.
+
+The next day, looking at your Agenda, you see the TODO and decide to
+respond to the email. You call `gnorb-org-handle-mail' on the heading,
+and Gnorb opens Jimmy's email and starts a reply to it.
+
+You tell Jimmy the room's available in March, and send the message.
+Gnorb takes you back to the heading, and asks you to trigger an action
+on it. You choose "todo state", and change the heading keyword to
+WAIT.
+
+Two days later, Jimmy replies to your message, saying that March is
+perfect. When you open his response, Gnorb politely reminds you that
+the message is relevant to an existing TODO. You call
+`gnorb-gnus-incoming-do-todo' on the message, and are again taken to
+the TODO and asked to trigger an action. Again you choose "todo
+state", and change the heading keyword back to REPLY.
+
+You get another email, from Samantha, warning you not to rent the room
+to Jimmy. She even attaches a picture of a room in her house, as it
+looked after Jimmy had stayed there for six months. It's bad. You call
+`gnorb-gnus-incoming-do-todo' on her message, and pick the "Jimmy
+renting a room" heading. This time, you choose "take note" as the
+trigger action, and make a brief note about how bad that room looked.
+Gnorb asks if you'd like to attach the picture to the Org heading. You
+decide you will.
+
+Now it's time to write to Jimmy and say something noncommittal.
+Calling `gnorb-org-handle-mail' on the heading would respond to
+Samantha's email, the most recent of the associated messages, which
+isn't what you want. Instead you call `gnorb-org-view' on the heading,
+which opens up a Gnus *Summary* buffer containing all four messages:
+Jimmy's first, your response, his response to that, and Samantha's
+message. You pick Jimmy's second email, and reply to it normally.
+Gnorb asks if you'd like to send the picture of the room as an
+attachment. You would not. When you send the reply Gnorb tracks that
+as well, and does the "trigger an action" trick again.
+
+In this way Gnorb helps you manage an entire conversation, possibly
+with multiple threads and multiple participants. Mostly all you need
+to do is call `gnorb-gnus-incoming-do-todo' on newly-received
+messages, and `gnorb-org-handle-mail' on the heading when it's time to
+compose a new reply.
+* Restoring Window Layout
+Many Gnorb functions alter the window layout and value of point. In
+most of these cases, you can restore the previous layout using the
+interactive function `gnorb-restore-layout'.
+
+* Recent Mails From BBDB Contacts
+:PROPERTIES:
+:END:
+If you're using a recent git version of BBDB (circa mid-May 2014 or
+later), you can give your BBDB contacts a special field which will
+collect links to recent emails from that contact. The default name of
+the field is "messages", but you can customize that name using the
+`gnorb-bbdb-messages-field' option.
+
+Gnorb will not collect links by default: you need to call
+`gnorb-bbdb-open-link' on a contact once to start the process.
+Thereafter, opening mails from that contact will store a link to the
+message.
+
+Once some links are stored, `gnorb-bbdb-open-link' will open them: Use
+a prefix arg to the function call to select particular messages to
+open. There are several options controlling how all this works; see
+the gnorb-bbdb user options section below for details.
+* BBDB posting styles
+:PROPERTIES:
+:END:
+Gnorb comes with a BBDB posting-style system, inspired by (copied
+from) gnus-posting-styles. You can specify how messages are composed
+to specific contacts, by matching on contact field values (the same
+way gnus-posting-styles matches on group names). See the docstring of
+`gnorb-bbdb-posting-styles' for details.
+
+In order not to be too intrusive, Gnorb doesn't alter the behavior of
+`bbdb-mail', the usual mail-composition function. Instead it provides
+an alternate `gnorb-bbdb-mail', which does exactly the same thing, but
+first processes the new mail according to `gnorb-bbdb-posting-styles'.
+If you want to use this feature regularly, you can remap `bbdb-mail'
+to `gnorb-bbdb-mail' in the `bbdb-mode-map'.
+* BBDB Org tagging
+BBDB contacts can be tagged with the same tags you use in your Org
+files. This allows you to pop up a *BBDB* buffer alongside your Org
+Agenda when searching for certain tags. This can happen automatically
+for all Org tags-todo searches, if you set the option
+`gnorb-org-agenda-popup-bbdb' to t. Or you can do it manually, by
+calling the command of the same name. This command only shows TODOs by
+default: use a prefix argument to show all tagged headings.
+
+Tags are stored in an xfield named org-tags, by default. You can
+customize the name of this field using `gnorb-bbdb-org-tag-field'.
+* Misc BBDB
+** Searching for messages from BBDB contacts
+:PROPERTIES:
+:END:
+Call `gnorb-bbdb-mail-search' to search for all mail messages from the
+record(s) displayed. Currently supports the notmuch, mairix, and
+namazu search backends; set `gnorb-gnus-mail-search-backend' to one of
+those symbol values.
+** Citing BBDB contacts
+:PROPERTIES:
+:END:
+Calling `gnorb-bbdb-cite-contact' will prompt for a BBDB record and
+insert a string of the type "Bob Smith <bob@smith.com>".
+** User Options
+- `gnorb-bbdb-org-tag-field :: The name of the BBDB xfield, as a
+ symbol, that holds Org-related tags. Specified as a string with
+ the ":" separator between tags, same as for Org headings.
+ Defaults to org-tag.
+- `gnorb-bbdb-messages-field' :: The name of the BBDB xfield that
+ holds links to recently-received messages from this contact.
+ Defaults to 'messages.
+- `gnorb-bbdb-collect-N-messages' :: Collect at most this many links
+ to messages from this contact. Defaults to 5.
+- `gnorb-bbdb-define-recent' :: What does "recently-received" mean?
+ Possible values are the symbols seen and received. When set to
+ seen, the most recently-opened messages are collected. When set
+ to received, the most recently-received (by Date header) messages
+ are collected. Defaults to seen.
+- `gnorb-bbdb-message-link-format-multi' :: How is a single message's
+ link formatted in the multi-line BBDB layout format? Defaults to
+ "%:count. %D: %:subject" (see the docstring for details).
+- ` gnorb-bbdb-message-link-format-one' :: How is a single message's
+ link formatted in the one-line BBDB layout format? Defaults to
+ nil (see the docstring for details).
+- `gnorb-bbdb-posting-styles' :: Styles to use for influencing the
+ format of mails composed to the BBDB record(s) under point (see
+ the docstring for details).
+* Misc Org
+** Inserting BBDB links
+:PROPERTIES:
+:END:
+Calling `gnorb-org-contact-link' will prompt for a BBDB record and
+insert an Org link to that record at point.
+** User Options
+- `gnorb-org-after-message-setup-hook' :: Hook run in a message buffer
+ after setting up the message, from `gnorb-org-handle-mail' or
+ `gnorb-org-email-subtree'.
+- `gnorb-org-trigger-actions' :: List of potential actions that can be
+ taken on headings after a message is sent. See docstring for
+ details.
+- `gnorb-org-mail-scan-scope' :: The number of paragraphs to scan for
+ mail-related links. This comes into play when calling
+ `gnorb-org-handle-mail' on a heading with no associated messages,
+ or when `gnorb-org-handle-mail' is called with a prefix arg.
+- `gnorb-org-find-candidates-match' :: When searching all Org files
+ for headings to collect messages from, this option can limit
+ which headings are searched. It is used as the second argument to
+ a call to `org-map-entries', and has the same syntax as that used
+ in an agenda tags view.
+- `gnorb-org-email-subtree-text-parameters' :: A plist of export
+ parameters corresponding to the EXT-PLIST argument to the export
+ functions, for use when exporting to text.
+- `gnorb-org-email-subtree-file-parameters' :: A plist of export
+ parameters corresponding to the EXT-PLIST argument to the export
+ functions, for use when exporting to a file.
+- `gnorb-org-email-subtree-text-options' :: A list of ts and nils
+ corresponding to Org's export options, to be used when exporting
+ to text. The options, in order, are async, subtreep,
+ visible-only, and body-only.
+- `gnorb-org-email-subtree-file-options' :: A list of ts and nils
+ corresponding to Org's export options, to be used when exporting
+ to a file. The options, in order, are async, subtreep,
+ visible-only, and body-only.
+- `gnorb-org-export-extensions' :: Correspondence between export
+ backends and their respective (usual) file extensions.
+- `gnorb-org-capture-collect-link-p' :: When this is set to t, the
+ capture process will always store a link to the Gnus message or
+ BBDB record under point, even when the link isn't part of the
+ capture template. It can then be added to the captured heading
+ with org-insert-link, as usual.
+- `gnorb-org-agenda-popup-bbdb' :: Set to "t" to automatically pop up
+ the BBDB buffer displaying records corresponding to the Org
+ Agenda tags search underway. If this is nil you can always do it
+ manually with the command of the same name.
+- `gnorb-org-bbdb-popup-layout' :: Controls the layout of the
+ Agenda-related BBDB popup, takes the same values as
+ bbdb-pop-up-layout.
+* Misc Gnus
+** Viewing Org headlines relevant to a message
+:PROPERTIES:
+:END:
+Call `gnorb-gnus-view' on a message that is associated with an Org
+heading to jump to that heading.
+** User Options
+- `gnorb-gnus-mail-search-backend' :: Specifies the search backend
+ that you use for searching mails. Currently supports notmuch,
+ mairix, and namazu: set this option to one of those symbols.
+- `gnorb-gnus-capture-always-attach' :: Treat all capture templates as
+ if they had the :gnus-attachments key set to "t". This only has
+ any effect if you're capturing from a Gnus summary or article
+ buffer.
+- `gnorb-trigger-todo-default' :: Set to either 'note or 'todo to tell
+ `gnorb-gnus-incoming-do-todo' what to do by default. You can
+ reach the non-default behavior by calling that function with a
+ prefix argument. Alternately, set to 'prompt to always prompt for
+ the appropriate action.
+- `gnorb-gnus-trigger-refile-targets' :: If you use
+ `gnorb-gnus-incoming-do-todo' on an incoming message, Gnorb will
+ try to locate a TODO heading that's relevant to that message. If
+ it can't, it will prompt you for one, using the refile interface.
+ This option will be used as the value of `org-refile-targets'
+ during that process: see the docstring of `org-refile-targets'
+ for the appropriate syntax.
+- `gnorb-gnus-new-todo-capture-key' :: Set this to a single-character
+ string pointing at an Org capture template to use when creating
+ TODOs from outgoing messages. The template is a regular capture
+ template, with a few exceptions. If Gnus helps you archive
+ outgoing messages (ie you have `gnus-message-archive-group' set
+ to something, and your outgoing messages have a "Fcc" header), a
+ link to that message will be made, and you'll be able to use all
+ the escapes related to gnus messages. If you don't archive
+ outgoing messages, you'll still be able to use the %:subject,
+ %:to, %:toname, %:toaddress, and %:date escapes in the capture
+ template.
+- `gnorb-gnus-hint-relevant-article' :: Set to "t" (the default) to
+ have Gnorb give you a hint in the minibuffer when opening
+ messages that might be relevant to existing Org TODOs.
+- `gnorb-gnus-summary-mark-format-letter' :: The formatting letter to
+ use as part of your `gnus-summary-line-format', to indicate
+ messages which might be relevant to Org TODOs. Defaults to "g",
+ meaning it should be used as "%ug" in the format line.
+- `gnorb-gnus-summary-mark' :: The mark used to indicate relevant
+ messages in the Summary buffer, when
+ `gnorb-gnus-summary-mark-format-letter' is present in the format
+ line. Defaults to "¡".
+* Suggested Keybindings
+:PROPERTIES:
+:ID: de1b2579-86c2-4bb1-b77e-3467a3d2b3c7
+:END:
+#+BEGIN_SRC emacs-lisp
+ (eval-after-load "gnorb-bbdb"
+ '(progn
+ (define-key bbdb-mode-map (kbd "O") 'gnorb-bbdb-tag-agenda)
+ (define-key bbdb-mode-map (kbd "S") 'gnorb-bbdb-mail-search)
+ (define-key bbdb-mode-map [remap bbdb-mail] 'gnorb-bbdb-mail)
+ (define-key bbdb-mode-map (kbd "l") 'gnorb-bbdb-open-link)
+ (global-set-key (kbd "C-c C") 'gnorb-bbdb-cite-contact)))
+
+ (eval-after-load "gnorb-org"
+ '(progn
+ (org-defkey org-mode-map (kbd "C-c C") 'gnorb-org-contact-link)
+ (org-defkey org-mode-map (kbd "C-c t") 'gnorb-org-handle-mail)
+ (org-defkey org-mode-map (kbd "C-c e") 'gnorb-org-view)
+ (org-defkey org-mode-map (kbd "C-c E") 'gnorb-org-email-subtree)
+ (org-defkey org-mode-map (kbd "C-c V") 'gnorb-org-popup-bbdb)
+ (setq gnorb-org-agenda-popup-bbdb t)
+ (eval-after-load "org-agenda"
+ '(progn (org-defkey org-agenda-mode-map (kbd "H") 'gnorb-org-handle-mail)
+ (org-defkey org-agenda-mode-map (kbd "V") 'gnorb-org-popup-bbdb)))))
+
+ (eval-after-load "gnorb-gnus"
+ '(progn
+ (define-key gnus-summary-mime-map "a" 'gnorb-gnus-article-org-attach)
+ (define-key gnus-summary-mode-map (kbd "C-c t") 'gnorb-gnus-incoming-do-todo)
+ (push '("attach to org heading" . gnorb-gnus-mime-org-attach)
+ gnus-mime-action-alist)
+ ;; The only way to add mime button command keys is by redefining
+ ;; gnus-mime-button-map, possibly not ideal. Ideal would be a
+ ;; setter function in gnus itself.
+ (push '(gnorb-gnus-mime-org-attach "a" "Attach to Org heading")
+ gnus-mime-button-commands)
+ (setq gnus-mime-button-map
+ (let ((map (make-sparse-keymap)))
+ (define-key map gnus-mouse-2 'gnus-article-push-button)
+ (define-key map gnus-down-mouse-3 'gnus-mime-button-menu)
+ (dolist (c gnus-mime-button-commands)
+ (define-key map (cadr c) (car c)))
+ map))))
+
+ (eval-after-load "message"
+ '(progn
+ (define-key message-mode-map (kbd "C-c t") 'gnorb-gnus-outgoing-do-todo)))
+#+END_SRC
+* Wishlist/TODO
+- Provide a command that, when in the Org Agenda, does an email search
+ for messages received in the visible date span, or day under point,
+ etc. Make it work in the calendar, as well?
+- Add trigger actions that create new sibling or child headings on the
+ original Org heading.
+- Allow tagging of Gnus messages, by giving the message's registry
+ entry an 'org-tags key.
+- Provide persistent nngnorb search groups.
+- Allow automatic org-tagging of BBDB contacts: when messages from a
+ contact are associated with an Org heading, make it possible for the
+ contact to inherit that heading's tags automatically.
+- Provide completion when setting Org tags on a BBDB contact.
+- Provide a `gnorb-bbdb-view' command that opens a *Summary* buffer
+ containing all the tracked messages from the contact(s) under point.
+- Provide a `gnorb-view' command that takes a tags-todo search phrase
+ (or a single Org heading ID), finds all relevant messages, Org
+ headings, and BBDB records, and sets up a four-pane view: Org
+ Agenda, *BBDB* buffer, Gnus *Summary* buffer, and an *Article*
+ buffer.