Allow bi-directional communication with mailman.

src/mailman.scm

@@ -77,6 +77,14 @@
     get-process-output-lines
     (mailman-bin bin)
     args))
+
+ ;; Sends all lines to the process
+ (define (mailman-send/recv bin args . lines)
+   (apply
+    process-send/recv
+    (mailman-bin bin)
+    args
+    lines))
     
  ;; Returns the list of available lists
  (define (list-mailman-lists)