365 lines
15 KiB
EmacsLisp
365 lines
15 KiB
EmacsLisp
;;; db-mail.el --- Utility Functions for sending mail -*- lexical-binding: t -*-
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;;; Commentary:
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;; This package consists mostly of utility functions for sending and editing
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;; mail and extending Gnus in the way I like it. However, the most important
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;; feature of is an abstract way to hande remote mail accounts. Theses are
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;; stored in the variable `db/mail-accounts’ and consist of various entries
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;; denoting how to read mail via IMAP (POP not supported) and how to send mail
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;; via SMTP (server, port, protocol, …). Based on the entries in this variable,
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;; appropriate settings of `gnus-secondary-select-methods’ are derived
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;; automatically by the custom setter of `db/mail-accounts’. Then when inside
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;; Gnus, the mail can be read without further configuration. Note that when the
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;; "IMAP address" of an entry in `db/mail-accounts’ is empty, it will not be
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;; included as an IMAP account in `gnus-secondary-select-methods’. This let’s
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;; you specify mail accounts that can be used for sending mail, but that are
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;; read not directly via IMAP, but by other means (POP, offlineimap, …).
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;; When sending mail, `db/mail-accounts’ is used to determine settings of the
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;; relevant variables from `smtpmail’ based on the current value of the "From: "
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;; header entry in the mail. If this header entry is set correctly, then
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;; `db/smtpmail-send-it’ will set these variables automatically. To make this
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;; work, however, two things have to be done:
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;;
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;; - Ensure that the "From: " header is set correctly. In Gnus this can be done
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;; by configuring `gnus-posting-style’ accordingly.
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;;
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;; - Make sure `db/smtpmail-send-it’ is called when sending mail. For this set
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;; the value `send-mail-function’ to `db/smtpmail-send-it’.
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;; All this functionality is provided under "Mail related customizations". The
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;; other headlines provide the aforementioned utility functions.
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;;; Code:
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(require 'subr-x)
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(require 'cl-lib)
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(require 'cl-macs)
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(require 'mail-extr)
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(require 'epg)
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(require 'mml-sec)
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(require 'gnus)
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(require 'gnus-start)
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(require 'smtpmail) ; to have the globals bound below by let
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(require 'message)
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(require 'db-customize)
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(declare-function gnus-summary-select-article-buffer "gnus-sum")
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(declare-function gnus-mime-pipe-part "gnus-art")
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;; Mail related customizations
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;; See definition of `db/mail-accounts’ below, sorry for the scatter …
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(defsubst db/mail-accounts--mail-address (account)
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"Extract account mail address from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 0 account))
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(defsubst db/mail-accounts--name (account)
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"Extract account name from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 1 account))
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(defsubst db/mail-accounts--imap-address (account)
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"Extract account IMAP address from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 2 account))
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(defsubst db/mail-accounts--smtp-server (account)
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"Extract account SMTP server address from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 3 account))
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(defsubst db/mail-accounts--smtp-stream-type (account)
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"Extract account SMTP stream type from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 4 account))
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(defsubst db/mail-accounts--smtp-service-port (account)
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"Extract account SMTP port from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 5 account))
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(defsubst db/mail-accounts--smtp-user (account)
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"Extract account SMTP user from ACCOUNT.
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ACCOUNT must be a valid element of `db/mail-accounts’."
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(nth 6 account))
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(defun db/-set-gnus-secondary-select-methods (other-gnus-accounts remote-mail-accounts)
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"Set `gnus-secondary-select-methods’ from OTHER-GNUS-ACCOUNTS and REMOTE-MAIL-ACCOUNTS.
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The values of the latter two variables are usually those of
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`db/other-gnus-accounts’ and `db/mail-accounts’. If multiple
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accounts exist with the same (cl-equalp) account name, only the
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first will be added to `gnus-secondary-select-methods'."
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(let ((select-methods (append other-gnus-accounts
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;; Only add those remote accounts whose IMAP address is neither
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;; `nil’ nor the empty string
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(cl-remove-if #'null
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(mapcar (lambda (account)
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(let ((account-name (db/mail-accounts--name account))
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(account-address (db/mail-accounts--imap-address account)))
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(when (and account-address
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(stringp account-address)
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(< 0 (length account-address)))
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`(nnimap ,account-name
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(nnimap-address ,account-address)
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(nnimap-stream starttls)
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(nnimap-inbox "INBOX")))))
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remote-mail-accounts)))))
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(setq gnus-secondary-select-methods
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(cl-remove-duplicates select-methods
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:key #'cl-second ; account name is second element
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:test #'cl-equalp))))
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;; Let's make the byte-compiler happy
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(defvar gnus-posting-styles)
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(defvar bbdb-user-mail-address-re)
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(defvar message-dont-reply-to-names)
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(defvar gnus-ignored-from-addresses)
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(defun db/mail-accounts--set-value (symbol value)
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"Set SYMBOL to VALUE, as needed for `db/mail-accounts’."
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(cl-assert (eq symbol 'db/mail-accounts)
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nil
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"Only use `db/mail-accounts--set-value’ for setting `db/mail-accounts’.")
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(set-default symbol value)
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;; Set `gnus-secondary-select-methods’
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(db/-set-gnus-secondary-select-methods
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;; Don’t complain if `db/other-gnus-accounts’ is not defined yet
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(and (boundp 'db/other-gnus-accounts) db/other-gnus-accounts)
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value)
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;; Set posting styles based on existing mail addresses
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(setq gnus-posting-styles
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(append
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`((".*"
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(name ,user-full-name)
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(address ,user-mail-address)
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(signature-file "~/.signature")
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("X-Jabber-ID" ,db/jabber-id)))
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(mapcar (lambda (account)
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(let ((account-name (db/mail-accounts--name account))
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(account-address (db/mail-accounts--mail-address account)))
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`(,(concat account-name ":")
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(name ,user-full-name)
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(address ,account-address)
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(signature-file "~/.signature")
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("X-Jabber-ID" ,db/jabber-id))))
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value)))
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;; Update some variables
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(setq bbdb-user-mail-address-re (regexp-opt (mapcar #'car value) 'words)
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message-dont-reply-to-names (regexp-opt (mapcar #'car value) 'words)
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gnus-ignored-from-addresses message-dont-reply-to-names))
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(defcustom db/mail-accounts nil
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"Configuration for remote email accounts.
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This is a list of lists, where each such list specifies necessary
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parameters for one particular email address. These addresses
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will also be recognized when sending mail."
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:group 'personal-settings
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:type '(repeat
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(list
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(string :tag "EMail Address")
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(string :tag "Group Name")
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(string :tag "IMAP Server Address (StartTLS)")
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(string :tag "SMTP Server Address")
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(choice :tag "SMTP Stream Type"
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(const nil) (const starttls) (const plain) (const ssl))
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(integer :tag "SMTP Service Port")
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(string :tag "SMTP Login Name")))
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:set #'db/mail-accounts--set-value)
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(defun db/smtpmail-send-it ()
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"Send prepared message in current buffer.
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This function uses `message-smtpmail-send-it’, but sets
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`smtpmail-smtp-server’, `smtpmail-stream-type’,
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`smtpmail-smtp-service’, and `smtpmail-smtp-user’ based on the
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entry of the \"From: \" header and the value of
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`db/mail-accounts’."
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(let* ((from (or (save-restriction
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(message-narrow-to-headers)
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(mail-fetch-field "From"))
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user-mail-address))
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(address (cadr (mail-extract-address-components from)))
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(account (assoc address db/mail-accounts)))
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(message "Using address: %s" address)
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(condition-case signal-data
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(if account
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(progn
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(message "Sending with account for %s" address)
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(let ((smtpmail-smtp-server (db/mail-accounts--smtp-server account))
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(smtpmail-stream-type (db/mail-accounts--smtp-stream-type account))
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(smtpmail-smtp-service (db/mail-accounts--smtp-service-port account))
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(smtpmail-smtp-user (db/mail-accounts--smtp-user account)))
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(cl-assert (cl-notany #'null (list smtpmail-smtp-server
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smtpmail-stream-type
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smtpmail-smtp-service
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smtpmail-smtp-user))
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t
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"Settings %s for sending mail are not complete for account %s."
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address)
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(message-smtpmail-send-it)))
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(if (yes-or-no-p "Sending with default account settings?")
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(message-smtpmail-send-it)
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(message "Sending aborted as requested by user.")))
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;; in case of error, display the SMTP trace buffer if available
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(error (when-let ((smtp-trace-buffer (get-buffer (format "*trace of SMTP session to %s*"
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smtpmail-smtp-server))))
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(shrink-window-if-larger-than-buffer (display-buffer smtp-trace-buffer)))
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(signal (car signal-data) (cdr signal-data))))))
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;; Setting other Gnus accounts
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(defun db/other-gnus-accounts--set-value (symbol value)
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"Set SYMBOL to VALUE as needed by `db/other-gnus-accounts’"
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(cl-assert (eq symbol 'db/other-gnus-accounts)
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nil
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"Only use `db/other-gnus-accounts--set-value’ for setting `db/other-gnus-accounts’.")
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(set-default symbol value)
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(db/-set-gnus-secondary-select-methods
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value
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;; Don’t complain if `db/mail-accounts’ is not defined yet.
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(and (boundp 'db/mail-accounts) db/mail-accounts)))
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(defcustom db/other-gnus-accounts nil
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"Configuration for gnus accounts that are not IMAP/SMTP related.
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Those are all accounts that are not derived from the entries in
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`db/mail-accounts’. The value of this variable should be a valid
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value for `gnus-secondary-select-methods’."
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:group 'personal-settings
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;; type definition for `gnus-select-method’ widget from gnus.el
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:type '(repeat gnus-select-method)
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:set #'db/other-gnus-accounts--set-value)
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;; Functions related to email encryption
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(defun db/public-key (address &optional method)
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"Return valid public keys for ADDRESS and given METHOD.
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METHOD can be \"smime\" or \"pgpmime\"; defaults to \"pgpmime\".
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ADDRESS is a string containing exactly one email address."
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(cl-check-type address string)
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(unless method (setq method "pgpmime"))
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(epg-list-keys (epg-make-context
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(cond
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((string= method "smime")
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'CMS)
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((string= method "pgpmime")
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'OpenPGP)
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(t (error "Unknown method %s" method))))
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address))
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(defun db/encryption-possible-p (recipients method)
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"Check whether sending encrypted emails to all RECIPIENTS is possible.
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METHOD specifies the encrypt method used. Can be either
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\"smime\" or \"pgpmime\"."
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(cl-every (lambda (recipient)
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(not (null (db/public-key recipient method))))
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recipients))
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(defun db/message-recipients ()
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"Return all recipients of the email in the current buffer."
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(cl-mapcan (lambda (field)
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(let ((field-value (message-field-value field)))
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(when field-value
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(mapcar #'cadr
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(mail-extract-address-components field-value t)))))
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(list "to" "cc" "bcc")))
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(defun db/signencrypt-message-when-possible ()
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"Add mml markers for signing and encryption of an email if possible."
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(interactive)
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(when (eq major-mode 'message-mode)
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(let ((from (message-field-value "from")))
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(when from
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(let ((methods (if (string-match "@tu-dresden\.de>" from)
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(list "smime" "pgpmime")
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(list "pgpmime")))
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(recipients (db/message-recipients)))
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;; if there is no recipient, encrypt with default method
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(if (null recipients)
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(mml-secure-message (cl-first methods) 'signencrypt)
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;; go through available keys
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(let ((available-method
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(cl-find-if (lambda (method)
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(db/encryption-possible-p recipients method))
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methods)))
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(if available-method
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(mml-secure-message available-method 'signencrypt)
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;; if nothing works, sign with default method
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(mml-secure-message (cl-first methods) 'sign)))))))))
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;; Gnus utility functions
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(defun db/gnus-save-newsrc-with-whitespace-1 ()
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"Save ~/.newsrc.eld with extra whitespace."
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;; http://ding.gnus.narkive.com/pq3Z8ZjQ/pretty-printing-newsrc-eld#post3
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(gnus-message 5 "Adding whitespace to .newsrc.eld")
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(save-excursion
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(goto-char (point-min))
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(while (re-search-forward "(\\\"\\| ((\\| (nn" nil t)
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(replace-match "\n \\&" t))
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(delete-trailing-whitespace)))
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(defun db/gnus-summary-open-Link ()
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"Open link named \"Link\" in current article."
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(interactive)
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(save-window-excursion
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(save-mark-and-excursion
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(save-restriction
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(widen)
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(let ((url nil))
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(unless (eq major-mode 'gnus-article-mode)
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(gnus-summary-select-article-buffer))
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(goto-char (point-min))
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(while (and (not url)
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(search-forward "Link"))
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(backward-char)
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(setq url (get-text-property (point) 'shr-url)))
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(when url
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(browse-url url)))))))
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(defun db/gnus-html-mime-part-to-org ()
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"Convert current gnus article to org mode."
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(interactive)
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(let ((return-code (gnus-mime-pipe-part "pandoc -f html -t org")))
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(unless (zerop return-code)
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(error "Error in extracting text"))
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(with-current-buffer "*Shell Command Output*"
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(kill-ring-save (point-min) (point-max)))))
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(defun db/gnus-demon-scan-news-on-level-2 ()
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"Scan for news in Gnus on level 2."
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;; from https://www.emacswiki.org/emacs/GnusDemon
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(let ((win (current-window-configuration))
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(gnus-read-active-file 'some)
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(gnus-check-new-newsgroups nil)
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(level 2))
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(while-no-input
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(unwind-protect
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(save-window-excursion
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(when (gnus-alive-p)
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(with-current-buffer gnus-group-buffer
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(gnus-group-get-new-news level))))
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(set-window-configuration win)))))
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(provide 'db-mail)
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;;; db-mail ends here
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