Mu4e: add support for non-@gmail gmail accounts

modules/email/mu4e/README.org

@@ -127,7 +127,8 @@ sudo apt-get install maildir-utils mu4e # mu and mu4e respectivly
     setting ~+org-msg-accent-color~)
 + Gmail integrations with the =+gmail= flag, which account for the different behaviour.
   This is applied when using addresses which contain =@gmail.com= or have =gmail= in
-  the maildir name.
+  the maildir name. You can use ~+mu4e-gmail-addresses~ when you want an address
+  to be treated as such but it meets neither conditions (e.g. with Gsuite).
 + Email notifications with =mu4e-alert=, and (on Linux) a customised notification style
 
 * Configuration

modules/email/mu4e/config.el

@@ -364,10 +364,18 @@ Must be set before org-msg is loaded to take effect.")
 
 (when (featurep! +gmail)
   (after! mu4e
+    (defvar +mu4e-gmail-addresses nil
+      "A list of email addresses which, despite not:
+- having '@gmail.com' in them, or
+- being in a maildir where the name includes 'gmail'
+
+Should be treated as a gmail address.")
+
     ;; don't save message to Sent Messages, Gmail/IMAP takes care of this
     (setq mu4e-sent-messages-behavior
           (lambda () ;; TODO make use +mu4e-msg-gmail-p
-            (if (string-match-p "@gmail.com\\'" (message-sendmail-envelope-from))
+            (if (or (string-match-p "@gmail.com\\'" (message-sendmail-envelope-from))
+                    (member (message-sendmail-envelope-from) +mu4e-gmail-addresses))
                 'delete 'sent))
 
           ;; don't need to run cleanup after indexing for gmail
@@ -382,10 +390,12 @@ Must be set before org-msg is loaded to take effect.")
        (string-match-p "@gmail.com"
                        (cond
                         ((member (mu4e-message-field msg :to)
-                                 (plist-get mu4e~server-props :personal-addresses))
+                                 (append (mu4e-personal-addresses)
+                                         +mu4e-gmail-addresses))
                          (mu4e-message-field msg :to))
                         ((member (mu4e-message-field msg :from)
-                                 (plist-get mu4e~server-props :personal-addresses))
+                                 (append (mu4e-personal-addresses)
+                                         +mu4e-gmail-addresses))
                          (mu4e-message-field msg :from))
                         (t "")))
        (string-match-p "gmail" (mu4e-message-field msg :maildir))))