diff --git a/mu4e/mu4e-utils.el b/mu4e/mu4e-utils.el
index 7a5f07de..f0ff52de 100644
--- a/mu4e/mu4e-utils.el
+++ b/mu4e/mu4e-utils.el
@@ -80,27 +80,48 @@ parameter (which may be `nil'), and return the result."
 	    (cond
 	      ((stringp   folder) folder)
 	      ((functionp folder) (funcall folder msg))
-	      (t (error "unsupported type for %S" folder)))))
+	      (t (mu4e-error "unsupported type for %S" folder)))))
     (or val (mu4e-error "%S evaluates to nil" foldervar))))
 
-(defun mu4e-get-drafts-folder (msg)
+(defun mu4e-get-drafts-folder (&optional msg)
   "Get the sent folder. See `mu4e-drafts-folder'."
   (mu4e~get-folder 'mu4e-drafts-folder msg))
 
-(defun mu4e-get-refile-folder (msg)
+(defun mu4e-get-refile-folder (&optional msg)
   "Get the folder for refiling. See `mu4e-refile-folder'."
   (mu4e~get-folder 'mu4e-refile-folder msg))
 
-(defun mu4e-get-sent-folder (msg)
+(defun mu4e-get-sent-folder (&optional msg)
   "Get the sent folder. See `mu4e-sent-folder'."
   (mu4e~get-folder 'mu4e-sent-folder msg))
 
-(defun mu4e-get-trash-folder (msg)
+(defun mu4e-get-trash-folder (&optional msg)
   "Get the sent folder. See `mu4e-trash-folder'."
   (mu4e~get-folder 'mu4e-trash-folder msg))
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; mu4e-attachment-dir is either a string or a function that takes a filename
+;; and the mime-type as argument, either (or both) which can be nil
+(defun mu4e~get-attachment-dir (&optional fname mimetype)
+  "Get the directory for saving attachments from
+`mu4e-attachment-dir' (which can be either a string or a function,
+see its docstring)."
+  (let
+    ((dir
+       (cond
+	 ((stringp mu4e-attachment-dir)
+	   mu4e-attachment-dir)
+	 ((functionp mu4e-attachment-dir)
+	   (funcall mu4e-attachment-dir fname mimetype))
+	 (t
+	   (mu4e-error "unsupported type for mu4e-attachment-dir" )))))
+    (if dir
+      (expand-file-name dir)
+      (mu4e-error (mu4e-error "mu4e-attachment-dir evaluates to nil")))))
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
 
 
 
@@ -543,13 +564,10 @@ This is used by the completion function in mu4e-compose."
     (mu4e-error "Please set `mu4e-maildir' to the full path to your
     Maildir directory."))
   ;; expand mu4e-maildir, mu4e-attachment-dir
-  (setq
-    mu4e-maildir (expand-file-name mu4e-maildir)
-    mu4e-attachment-dir (expand-file-name mu4e-attachment-dir))
+  (setq mu4e-maildir (expand-file-name mu4e-maildir))
   (unless (mu4e-create-maildir-maybe mu4e-maildir)
     (mu4e-error "%s is not a valid maildir directory" mu4e-maildir))
-  (dolist (var '(mu4e-sent-folder
-		  mu4e-drafts-folder
+  (dolist (var '(mu4e-sent-folder mu4e-drafts-folder
 		  mu4e-trash-folder))
     (unless (and (boundp var) (symbol-value var))
       (mu4e-error "Please set %S" var))
diff --git a/mu4e/mu4e-vars.el b/mu4e/mu4e-vars.el
index d44a9f02..690b1b13 100644
--- a/mu4e/mu4e-vars.el
+++ b/mu4e/mu4e-vars.el
@@ -73,7 +73,10 @@ mu4e."
   :safe 'integerp)
 
 (defcustom mu4e-attachment-dir (expand-file-name "~/")
-  "Default directory for saving attachments."
+  "Default directory for saving attachments. This can be either a
+string, or a function that takes a filename FNAME and MIMETYPE as
+arguments, and returns the attachment dir. Note, either or both of
+the arguments may be `nil'."
   :type 'directory
   :group 'mu4e
   :safe 'stringp)
diff --git a/mu4e/mu4e-view.el b/mu4e/mu4e-view.el
index 32b553fd..3d327f93 100644
--- a/mu4e/mu4e-view.el
+++ b/mu4e/mu4e-view.el
@@ -891,14 +891,14 @@ number ATTNUM."
   "Save attachment number ATTNUM (or ask if nil) from MSG (or
 message-at-point if nil) to disk."
   (interactive)
-  (unless mu4e-attachment-dir
-    (mu4e-error "`mu4e-attachment-dir' is not set"))
   (let* ((msg (or msg (mu4e-message-at-point)))
 	  (attnum (or attnum
 		    (mu4e~view-get-attach-num "Attachment to save" msg)))
 	  (att (mu4e~view-get-attach msg attnum))
-	  (path (concat mu4e-attachment-dir "/"))
 	  (fname  (plist-get att :name))
+	  (mtype  (plist-get att :mime-type))
+	  (path (concat
+		  (mu4e~get-attachment-dir fname mtype) "/"))
 	  (index (plist-get att :index))
 	  (retry t))
     (while retry
@@ -1053,7 +1053,7 @@ attachments) in response to a (mu4e~proc-extract 'temp ... )."
 (defun mu4e~view-split-view-p ()
   "Return t if we're in split-view, nil otherwise."
   (member mu4e-split-view '(horizontal vertical)))
-  
+
 (defun mu4e-view-unmark-all ()
   "If we're in split-view, unmark all messages. Otherwise, warn
 user that unmarking only works in the header list."