+PH/03 Added disable_ipv6.
+
+PH/04 Changed $reply_address to use the raw form of the headers instead of the
+ decoded form, because it is most often used to construct To: headers
+ lines in autoreplies, and the decoded form may well be syntactically
+ invalid. However, $reply_address has leading white space removed, and all
+ newlines turned into spaces so that the autoreply transport does not
+ grumble.
+