Index: tests/test_email.py
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/tests/test_email.py b/tests/test_email.py
--- a/tests/test_email.py   (revision 66726ef806ea2940870251b587a1ae07be9bc1af)
+++ b/tests/test_email.py   (revision afc778de29e4480f8f95b0517b385ed3728b370c)
@@ -20,6 +20,14 @@
     assert email(value, whitelist=whitelist)


[email protected](('value', 'local_characters_in_user'), [
+    ('emł[email protected]', "ł"),
+    ('łemł[email protected]', "ł"),
+])
+def test_returns_true_on_valid_email_with_local_characters_in_user(value, local_characters_in_user):
+    assert email(value, local_characters_in_user=local_characters_in_user)
+
+
 @pytest.mark.parametrize(('value',), [
     (None,),
     ('',),
Index: validators/email.py
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/validators/email.py b/validators/email.py
--- a/validators/email.py   (revision 66726ef806ea2940870251b587a1ae07be9bc1af)
+++ b/validators/email.py   (revision afc778de29e4480f8f95b0517b385ed3728b370c)
@@ -1,29 +1,34 @@
 import re

 from .utils import validator
+from functools import cache

-user_regex = re.compile(
-    # dot-atom
-    r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+"
-    r"(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*$"
-    # quoted-string
-    r'|^"([\001-\010\013\014\016-\037!#-\[\]-77]|'
-    r"""\\[\001-\011\013\014\016-77])*"$)""",
-    re.IGNORECASE
-)
-domain_regex = re.compile(
-    # domain
-    r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+'
-    r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?$)'
-    # literal form, ipv4 address (SMTP 4.1.3)
-    r'|^\[(25[0-5]|2[0-4]\d|[0-1]?\d?\d)'
-    r'(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\]$',
-    re.IGNORECASE)
+
+@cache
+def regex(local_characters_in_user=""):
+    return re.compile(
+        # dot-atom
+        r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z" + local_characters_in_user + "]+"
+        r"(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z" + local_characters_in_user + "]+)*$"
+        # quoted-string
+        r'|^"([\001-\010\013\014\016-\037!#-\[\]-77]|'
+        r"""\\[\001-\011\013\014\016-77])*"$)""",
+        re.IGNORECASE
+    ), re.compile(
+        # domain
+        r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+'
+        r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?$)'
+        # literal form, ipv4 address (SMTP 4.1.3)
+        r'|^\[(25[0-5]|2[0-4]\d|[0-1]?\d?\d)'
+        r'(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\]$',
+        re.IGNORECASE)
+
+
 domain_whitelist = ['localhost']


 @validator
-def email(value, whitelist=None):
+def email(value, whitelist=None, local_characters_in_user=""):
     """
     Validate an email address.

@@ -46,10 +51,12 @@

     :param value: value to validate
     :param whitelist: domain names to whitelist
+    :param local_characters_in_user: string with extra accepted characters in user part

     :copyright: (c) Django Software Foundation and individual contributors.
     :license: BSD
     """
+    user_regex, domain_regex = regex(local_characters_in_user)

     if whitelist is None:
         whitelist = domain_whitelist