diff --git a/django/utils/html.py b/django/utils/html.py
index bc336d88a6..0d107a0da9 100644
--- a/django/utils/html.py
+++ b/django/utils/html.py
@@ -357,6 +357,8 @@ class Urlizer:
                     domain = punycode(domain)
                 except UnicodeError:
                     return word
+                local = quote(local, safe="")
+                domain = quote(domain, safe="")
                 url = self.mailto_template.format(local=local, domain=domain)
                 nofollow_attr = ""
             # Make link.
diff --git a/tests/utils_tests/test_html.py b/tests/utils_tests/test_html.py
index dc3768e6fa..0beaf98bff 100644
--- a/tests/utils_tests/test_html.py
+++ b/tests/utils_tests/test_html.py
@@ -376,6 +376,19 @@ class TestUtilsHtml(SimpleTestCase):
                 + "한.글." * 15
                 + "aaa</a>",
             ),
+            (
+                # RFC 6068 requires a mailto URI to percent-encode a number of
+                # characters that can appear in <addr-spec>.
+                "yes;this=is&a%valid!email@example.com",
+                '<a href="mailto:yes%3Bthis%3Dis%26a%25valid%21email@example.com"'
+                ">yes;this=is&a%valid!email@example.com</a>",
+            ),
+            (
+                # Urlizer shouldn't urlize the "?org" part of this. But since
+                # it does, RFC 6068 requires percent encoding the "?".
+                "test@example.com?org",
+                '<a href="mailto:test@example.com%3Forg">test@example.com?org</a>',
+            ),
         )
         for value, output in tests:
             with self.subTest(value=value):