--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -159,17 +159,14 @@
         now = time.localtime(timeval)
         # Calculate timezone offset, based on whether the local zone has
         # daylight savings time, and whether DST is in effect.
-        if time.daylight and now[-1]:
-            offset = time.altzone
-        else:
-            offset = time.timezone
+        offset = now.tm_gmtoff
         hours, minutes = divmod(abs(offset), 3600)
         # Remember offset is in seconds west of UTC, but the timezone is in
         # minutes east of UTC, so the signs differ.
         if offset > 0:
-            sign = '-'
-        else:
             sign = '+'
+        else:
+            sign = '-'
         zone = '%s%02d%02d' % (sign, hours, minutes // 60)
     else:
         now = time.gmtime(timeval)