This patch adds environment variables to fastforward. Everything
between two dollar signs gets evaluated per delivery. Use a line
like "@some.domain: $EXT$@another.domain" to your aliases file to
do wildcard forwarding.    http://www.wolfermann.org/djbware.html
--- fastforward.c.orig	Tue May 19 18:25:42 1998
+++ fastforward.c	Tue Dec 14 11:29:57 2004
@@ -250,15 +250,37 @@ void dodata()
     }
 }
 
-void dorecip(addr)
+void dovar(addr)
 char *addr;
 {
+  int i,n;
+  char *x;
+  
+  for (i=0; addr[i]; i++) {
+    if (addr[i] == '$') {
+      n = str_chr(addr + i + 1, '$');
+      addr[i+n+1] = 0;
+      if ((x = env_get(addr+i+1)))
+        if (!stralloc_cats(&forward,x)) nomem();
+      i = i+n+1;
+    } else
+      if (!stralloc_catb(&forward,addr+i,1)) nomem();
+  }
+  if (!stralloc_0(&forward)) nomem();
+}
 
+void dorecip(addr)
+char *addr;
+{
   if (!findtarget(0,"?",addr))
     if (gettarget(0,":",addr)) {
       dodata();
       return;
     }
+  if (addr[str_rchr(addr, '$')]) {
+    dovar(addr);
+    return;
+  }
   if (!stralloc_cats(&forward,addr)) nomem();
   if (!stralloc_0(&forward)) nomem();
 }