[3.1.x] Fixed #31784 -- Fixed crash when sending emails on Python 3.6.11+, 3.7.8+, and 3.8.4+.

Fixed sending emails crash on email addresses with display names longer
then 75 chars on Python 3.6.11+, 3.7.8+, and 3.8.4+.

Wrapped display names were passed to email.headerregistry.Address()
what caused raising an exception because address parts cannot contain
CR or LF.

See https://bugs.python.org/issue39073

Co-Authored-By: Mariusz Felisiak <felisiak.mariusz@gmail.com>

Backport of 96a3ea39ef0790dbc413dde0a3e19f6a769356a2 from master

1 files changed, 12 insertions, 4 deletions

diff --git a/django/core/mail/message.py b/django/core/mail/message.py
index 607eb4af0b..963542cd62 100644
--- a/django/core/mail/message.py
+++ b/django/core/mail/message.py
@@ -10,7 +10,7 @@ from email.mime.base import MIMEBase
 from email.mime.message import MIMEMessage
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
-from email.utils import formatdate, getaddresses, make_msgid
+from email.utils import formataddr, formatdate, getaddresses, make_msgid
 from io import BytesIO, StringIO
 from pathlib import Path
 
@@ -96,16 +96,24 @@ def sanitize_address(addr, encoding):
         nm, address = addr
         localpart, domain = address.rsplit('@', 1)
 
-    nm = Header(nm, encoding).encode()
+    address_parts = nm + localpart + domain
+    if '\n' in address_parts or '\r' in address_parts:
+        raise ValueError('Invalid address; address parts cannot contain newlines.')
+
     # Avoid UTF-8 encode, if it's possible.
     try:
+        nm.encode('ascii')
+        nm = Header(nm).encode()
+    except UnicodeEncodeError:
+        nm = Header(nm, encoding).encode()
+    try:
         localpart.encode('ascii')
     except UnicodeEncodeError:
         localpart = Header(localpart, encoding).encode()
     domain = punycode(domain)
 
-    parsed_address = Address(nm, username=localpart, domain=domain)
-    return str(parsed_address)
+    parsed_address = Address(username=localpart, domain=domain)
+    return formataddr((nm, parsed_address.addr_spec))
 
 
 class MIMEMixin: