diff --git a/Lib/email/parser.py b/Lib/email/parser.py
--- a/Lib/email/parser.py
+++ b/Lib/email/parser.py
@@ -100,9 +100,9 @@
         meaning it parses the entire contents of the file.
         """
         fp = TextIOWrapper(fp, encoding='ascii', errors='surrogateescape')
-        with fp:
-            return self.parser.parse(fp, headersonly)
-
+        msg = self.parser.parse(fp, headersonly)
+        fp.detach()
+        return msg
 
     def parsebytes(self, text, headersonly=False):
         """Create a message structure from a byte string.