Set context-aware "from" address (mu4e)

The user can configure a list of addresses that are associated with a
context by passing a list to set-email-account!, e.g.

    (set-email-account! "foo"
      ...
      (+mu4e-personal-addresses ("foo@bar.org" "bar@baz.org")))

This list, if it exists, is used to prompt the user for the "from"
address after trying to set the "from" address automatically.

modules/email/mu4e/autoload/email.el

@@ -15,6 +15,7 @@ OPTIONAL:
  + `mu4e-trash-folder'
  + `mu4e-refile-folder'
  + `mu4e-compose-signature'
+ + `+mu4e-personal-adresses'
 
 DEFAULT-P is a boolean. If non-nil, it marks that email account as the
 default/fallback account."
@@ -194,19 +195,24 @@ is tomorrow.  With two prefixes, select the deadline."
                      (t         "later"))))))
 
 ;;;###autoload
-(defun +mu4e-set-account ()
+(defun +mu4e-set-from-address ()
   "Set the account for composing a message. If a 'To' header is present,
-and correspands to an email account, this account will be selected.
+and correspands to an email address, this address will be selected.
-Otherwise, the user is prompted for the account they wish to use."
+Otherwise, the user is prompted for the address they wish to use. Possible
+selections come from the mu database or a list of email addresses associated
+with the current context."
   (unless (and mu4e-compose-parent-message
                (let ((to (cdr (car (mu4e-message-field mu4e-compose-parent-message :to))))
                      (from (cdr (car (mu4e-message-field mu4e-compose-parent-message :from)))))
-                 (if (member to (plist-get mu4e~server-props :personal-addresses))
+                 (if (member to (mu4e-personal-addresses))
                      (setq user-mail-address to)
-                   (if (member from (plist-get mu4e~server-props :personal-addresses))
+                   (if (member from (mu4e-personal-addresses))
                        (setq user-mail-address from)
                      nil))))
-    (ivy-read "Account: " (plist-get mu4e~server-props :personal-addresses) :action (lambda (candidate) (setq user-mail-address candidate)))))
+    (ivy-read "From: " (if-let ((context-addresses (alist-get '+mu4e-personal-addresses (mu4e-context-vars mu4e~context-current))))
+                           context-addresses
+                         (mu4e-personal-addresses))
+              :action (lambda (candidate) (setq user-mail-address candidate)))))
 
 ;;;###autoload
 (defun +mu4e~main-action-str-prettier (str &optional func-or-shortcut)

modules/email/mu4e/config.el

@@ -3,6 +3,9 @@
 (defvar +mu4e-backend 'mbsync
   "Which backend to use. Can either be offlineimap, mbsync or nil (manual).")
 
+(defvar +mu4e-personal-adresses 'nil
+  "Alternative to mu4e-personal-adresses that can be set for each account (mu4e context).")
+
 
 ;;
 ;;; Packages
@@ -188,7 +191,7 @@
           :v "u" #'mu4e-headers-mark-for-unmark
           :vn "l" #'+mu4e-msg-to-agenda))
 
-  (add-hook 'mu4e-compose-pre-hook '+mu4e-set-account)
+  (add-hook 'mu4e-compose-pre-hook '+mu4e-set-from-address)
 
   (advice-add #'mu4e~main-action-str :override #'+mu4e~main-action-str-prettier)
   (when (featurep! :editor evil)