Index: Lib/email/test/test_email.py
===================================================================
--- Lib/email/test/test_email.py	(revision 87188)
+++ Lib/email/test/test_email.py	(working copy)
@@ -2319,6 +2319,24 @@
         eq(utils.parseaddr('"\\\\"example\\\\" example"@example.com'),
           ('', '"\\\\"example\\\\" example"@example.com'))
 
+    def test_parseaddr_preserves_spaces_in_local_part(self):
+        # issue 9286.  A normal RFC5322 local part should not contain any
+        # folding white space, but legacy local parts can (they are a sequence
+        # of atoms, not dotatoms).  On the other hand we strip whitespace from
+        # before the @ and around dots, on the assumption that the whitespace
+        # around the punctuation is a mistake in what would otherwise be
+        # an RFC5322 local part.  Leading whitespace is, usual, stripped as well.
+        self.assertEqual(('', "merwok wok@rusty.com"),
+            utils.parseaddr("merwok wok@rusty.com"))
+        self.assertEqual(('', "merwok  wok@rusty.com"),
+            utils.parseaddr("merwok  wok@rusty.com"))
+        self.assertEqual(('', "merwok  wok@rusty.com"),
+            utils.parseaddr(" merwok  wok  @rusty.com"))
+        self.assertEqual(('', 'merwok"wok"  wok@rusty.com'),
+            utils.parseaddr('merwok"wok"  wok@rusty.com'))
+        self.assertEqual(('', 'merwok.wok.wok@rusty.com'),
+            utils.parseaddr('merwok. wok .  wok@rusty.com'))
+
     def test_multiline_from_comment(self):
         x = """\
 Foo
Index: Lib/email/_parseaddr.py
===================================================================
--- Lib/email/_parseaddr.py	(revision 87188)
+++ Lib/email/_parseaddr.py	(working copy)
@@ -199,14 +199,18 @@
         self.commentlist = []
 
     def gotonext(self):
-        """Parse up to the start of the next address."""
+        """Skip white space and extract comments."""
+        wslist = []
         while self.pos < len(self.field):
             if self.field[self.pos] in self.LWS + '\n\r':
+                if self.field[self.pos] not in '\n\r':
+                    wslist.append(self.field[self.pos])
                 self.pos += 1
             elif self.field[self.pos] == '(':
                 self.commentlist.append(self.getcomment())
             else:
                 break
+        return EMPTYSTRING.join(wslist)
 
     def getaddrlist(self):
         """Parse all addresses.
@@ -319,16 +323,24 @@
 
         self.gotonext()
         while self.pos < len(self.field):
+            preserve_ws = True
             if self.field[self.pos] == '.':
+                if aslist and not aslist[-1].strip():
+                    aslist.pop()
                 aslist.append('.')
                 self.pos += 1
+                preserve_ws = False
             elif self.field[self.pos] == '"':
                 aslist.append('"%s"' % quote(self.getquote()))
             elif self.field[self.pos] in self.atomends:
+                if aslist and not aslist[-1].strip():
+                    aslist.pop()
                 break
             else:
                 aslist.append(self.getatom())
-            self.gotonext()
+            ws = self.gotonext()
+            if preserve_ws and ws:
+                aslist.append(ws)
 
         if self.pos >= len(self.field) or self.field[self.pos] != '@':
             return EMPTYSTRING.join(aslist)