mail: provide a way to set return address.

* mail/mail.c: New option -r (--return-address).
* mail/mailvar.c: New variable "return-address".
* mail/send.c (send_message): Obtain the return mail address
from the "return-address" variable (if set).

* NEWS: Update.
* doc/texinfo/programs.texi: Update.

-GNU mailutils NEWS -- history of user-visible changes. 2012-07-19
+GNU mailutils NEWS -- history of user-visible changes. 2012-08-07
 Copyright (C) 2002-2012 Free Software Foundation, Inc.
 See the end of file for copying conditions.
 
@@ -149,6 +149,17 @@ The mail shell provides the following new escapes to handle attachments:
  ~^ N
     Delete Nth attachment.
 
+** mail: the -r option
+
+The meaning of the `-r' option has changed.  Now it introduces the
+return address to use when sending mail.  This is an incompatible
+change.
+
+The return address can also be set from the mail shell, by assigning
+to the `return-address' variable, e.g.:
+
+ set return-address "gray@gnu.org"
+    
 ** MH: improved compatibility with other implementations
 
 ** MH inc: new option --moveto

@@ -2489,7 +2489,6 @@ Do not read the system-wide mailrc file.  @xref{Mail Configuration Files}.
 Do not display initial header summary.
 @item -p
 @itemx --print
-@itemx -r
 @itemx --read
 Print all mail to standard output.  It is equivalent to issuing following
 commands after starting @samp{mail -N}:
@@ -2499,6 +2498,9 @@ print *
 quit
 @end group
 @end example
+@item -r @var{address}
+@itemx --return-address=@var{address}
+Sets the return email address for outgoing mail.  @xref{return-address}.
 @item -q
 @itemx --quit
 Cause interrupts to terminate program.
@@ -4371,6 +4373,16 @@ set replyregex="^(re|odp|aw|ang)(\\[[0-9]+\\])?:[[:blank:]]"
 @noindent
 (Notice the quoting of backslash characters).
 
+@anchor{return-address}
+@kwindex return-address
+@item return-address
+@*Type: String
+@*Default: unset
+@vrindex return-address, mail variable.
+
+Sets the return email address to use when sending messages.  If unset,
+the address is composed from the current user name and the host name.
+
 @kwindex save
 @item save
 @*Type: Boolean.

@@ -47,7 +47,9 @@ static struct argp_option options[] = {
   {"nosum",   'N', NULL,      0,
    N_("do not display initial header summary"), 0},
   {"print",   'p', NULL,      0, N_("print all mail to standard output"), 0},
-  {"read",    'r', NULL,      OPTION_ALIAS },
+  {"read",    NULL, NULL,      OPTION_ALIAS },
+  {"return-address", 'r', N_("ADDRESS"), 0,
+   N_("use address as the return address when sending mail"), 0},
   {"quit",    'q', NULL,      0,
    N_("cause interrupts to terminate program"), 0},
   {"subject", 's', N_("SUBJ"), 0,
@@ -117,10 +119,13 @@ parse_opt (int key, char *arg, struct argp_state *state)
       break;
       
     case 'p':
-    case 'r':
       util_cache_command (&command_list, "setq mode=print");
       break;
       
+    case 'r':
+      util_cache_command (&command_list, "set return-address=%s", arg);
+      break;
+      
     case 'q':
       util_cache_command (&command_list, "set quit");
       break;

@@ -215,6 +215,9 @@ struct mailvar_symbol mailvar_tab[] =
       MAILVAR_TYPEMASK (mailvar_type_string),
       N_("regexp for recognizing subject lines of reply messages"),
       set_replyregex },
+    { { "return-address" },
+      MAILVAR_TYPEMASK (mailvar_type_string),
+      N_("return address for outgoing messages") },
     { { "save", },
       MAILVAR_TYPEMASK (mailvar_type_boolean),
       N_("store aborted messages in the user's dead.file") },

@@ -185,7 +185,7 @@ send_attach_file (const char *name,
   if (!encoding)
     encoding = "base64";
   mu_filter_get_list (&list);
-  rc = mu_list_locate (list, encoding, NULL);
+  rc = mu_list_locate (list, (void*) encoding, NULL);
   if (rc)
     {
       mu_error (_("unsupported encoding: %s"), encoding);
@@ -777,24 +777,43 @@ send_message (mu_message_t msg)
 	  status = mu_mailer_create (&mailer, sendmail);
 	  if (status == 0)
 	    {
+	      const char *return_address_str;
+	      mu_address_t return_address = NULL;
+	      
+	      if (mailvar_get (&return_address_str, "return-address",
+			       mailvar_type_string, 0) == 0)
+		{
+		  status = mu_address_create (&return_address,
+					      return_address_str);
+		  if (status)
+		    {
+		      mu_error (_("invalid return address: %s"),
+				mu_strerror (status));
+		      mu_mailer_destroy (&mailer);
+		      return status;
+		    }
+		} 
+
 	      if (mailvar_get (NULL, "verbose", mailvar_type_boolean, 0) == 0)
 		{
 		  mu_debug_set_category_level (MU_DEBCAT_MAILER,
-				      MU_DEBUG_LEVEL_UPTO (MU_DEBUG_PROT));
+					  MU_DEBUG_LEVEL_UPTO (MU_DEBUG_PROT));
 		}
 	      status = mu_mailer_open (mailer, MU_STREAM_RDWR);
 	      if (status == 0)
 		{
-		  status = mu_mailer_send_message (mailer, msg, NULL, NULL);
+		  status = mu_mailer_send_message (mailer, msg,
+						   return_address, NULL);
 		  mu_mailer_close (mailer);
 		}
 	      else
-		mu_error (_("Cannot open mailer: %s"), mu_strerror (status));
+		mu_error (_("Cannot open mailer: %s"),
+			  mu_strerror (status));
 	      mu_mailer_destroy (&mailer);
+	      mu_address_destroy (&return_address);
 	    }
 	  else
-	    mu_error (_("Cannot create mailer: %s"),
-			mu_strerror (status));
+	    mu_error (_("Cannot create mailer: %s"), mu_strerror (status));
 	}
     }
   else