diff --git a/django/core/mail/message.py b/django/core/mail/message.py
index 96ff689fd4..bed4966ef9 100644
--- a/django/core/mail/message.py
+++ b/django/core/mail/message.py
@@ -3,16 +3,21 @@ import os
 import random
 import time
 from email import Charset, Encoders
+from email.generator import Generator
 from email.MIMEText import MIMEText
 from email.MIMEMultipart import MIMEMultipart
 from email.MIMEBase import MIMEBase
 from email.Header import Header
-from email.Utils import formatdate, getaddresses, formataddr
+from email.Utils import formatdate, getaddresses, formataddr, parseaddr
 
 from django.conf import settings
 from django.core.mail.utils import DNS_NAME
 from django.utils.encoding import smart_str, force_unicode
-from email.Utils import parseaddr
+
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
 
 # Don't BASE64-encode UTF-8 messages so that we avoid unwanted attention from
 # some spam filters.
@@ -119,6 +124,19 @@ class SafeMIMEText(MIMEText):
         name, val = forbid_multi_line_headers(name, val, self.encoding)
         MIMEText.__setitem__(self, name, val)
 
+    def as_string(self, unixfrom=False):
+        """Return the entire formatted message as a string.
+        Optional `unixfrom' when True, means include the Unix From_ envelope
+        header.
+
+        This overrides the default as_string() implementation to not mangle
+        lines that begin with 'From '. See bug #13433 for details.
+        """
+        fp = StringIO()
+        g = Generator(fp, mangle_from_ = False)
+        g.flatten(self, unixfrom=unixfrom)
+        return fp.getvalue()
+
 
 class SafeMIMEMultipart(MIMEMultipart):
 
@@ -130,6 +148,19 @@ class SafeMIMEMultipart(MIMEMultipart):
         name, val = forbid_multi_line_headers(name, val, self.encoding)
         MIMEMultipart.__setitem__(self, name, val)
 
+    def as_string(self, unixfrom=False):
+        """Return the entire formatted message as a string.
+        Optional `unixfrom' when True, means include the Unix From_ envelope
+        header.
+
+        This overrides the default as_string() implementation to not mangle
+        lines that begin with 'From '. See bug #13433 for details.
+        """
+        fp = StringIO()
+        g = Generator(fp, mangle_from_ = False)
+        g.flatten(self, unixfrom=unixfrom)
+        return fp.getvalue()
+
 
 class EmailMessage(object):
     """
diff --git a/tests/regressiontests/mail/tests.py b/tests/regressiontests/mail/tests.py
index 8bdc562c81..224254c044 100644
--- a/tests/regressiontests/mail/tests.py
+++ b/tests/regressiontests/mail/tests.py
@@ -11,8 +11,8 @@ import threading
 
 from django.conf import settings
 from django.core import mail
-from django.core.mail import EmailMessage, mail_admins, mail_managers, EmailMultiAlternatives
-from django.core.mail import send_mail, send_mass_mail
+from django.core.mail import (EmailMessage, mail_admins, mail_managers,
+        EmailMultiAlternatives, send_mail, send_mass_mail)
 from django.core.mail.backends import console, dummy, locmem, filebased, smtp
 from django.core.mail.message import BadHeaderError
 from django.test import TestCase
@@ -282,6 +282,12 @@ class MailTests(TestCase):
         self.assertEqual(len(connection.test_outbox), 1)
         self.assertEqual(connection.test_outbox[0].subject, '[Django] Manager message')
 
+    def test_dont_mangle_from_in_body(self):
+        # Regression for #13433 - Make sure that EmailMessage doesn't mangle
+        # 'From ' in message body.
+        email = EmailMessage('Subject', 'From the future', 'bounce@example.com', ['to@example.com'], headers={'From': 'from@example.com'})
+        self.assertFalse('>From the future' in email.message().as_string())
+
 
 class BaseEmailBackendTests(object):
     email_backend = None