.

original commit: a943e41692a94267316c3f060a06a1d9b0992231

collects/mzlib/date.ss

@@ -44,7 +44,7 @@
   |#
 
   (define legal-formats
-    (list 'american 'chinese 'german 'indian 'irish 'julian 'iso-8601))
+    (list 'american 'chinese 'german 'indian 'irish 'julian 'iso-8601 'rfc822))
 
   (define date-display-format 
     (make-parameter 'american
@@ -142,6 +142,17 @@
 		 (values
 		  (list year "-" (add-zero (date-month date)) "-" (add-zero (date-day date)))
 		  (list " " hour24 ":" minute ":" second))]
+		[(rfc822)
+		 (values
+		  (list (substring week-day 0 3) ", " day " " (substring month 0 3) " " year)
+		  (list* " " hour24 ":" minute ":" second " "
+			 (let* ([delta (date-time-zone-offset date)]
+				[hours (quotient delta 3600)]
+				[minutes (modulo (quotient delta 60) 60)])
+			   (list
+			    (if (negative? delta) "-" "")
+			    (add-zero (abs hours))
+			    (add-zero minutes)))))]
 		[else (error 'date->string "unknown date-display-format: ~s"
 			     (date-display-format))])])
 	  (apply string-append (if time?

collects/net/head-unit.ss

@@ -1,6 +1,7 @@
 
 (module head-unit mzscheme
-  (require (lib "unitsig.ss"))
+  (require (lib "unitsig.ss")
+	   (lib "date.ss"))
 
   (require "head-sig.ss")
 
@@ -139,7 +140,10 @@
       (define (standard-message-header from tos ccs bccs subject)
 	(let ([h (insert-field
 		  "Subject" subject
-		  empty-header)])
+		  (insert-field 
+		   "Date" (parameterize ([date-display-format 'rfc822])
+			    (date->string (seconds->date (current-seconds)) #t))
+		   empty-header))])
 	  ;; NOTE: bccs don't go into the header; that's why
 	  ;; they're "blind"
 	  (let ([h (if (null? ccs)