Accept tagged IPv6 email address literals

src/validators/email.py

@@ -5,6 +5,7 @@
 
 # local
 from .hostname import hostname
+from .ip_address import ipv6
 from .utils import validator
 
 
@@ -39,7 +40,8 @@ def email(
         value:
             eMail string to validate.
         ipv6_address:
-            When the domain part is an IPv6 address.
+            When the domain part is an IPv6 address, including an RFC 5321
+            address literal such as `[IPv6:2001:db8::1]`.
         ipv4_address:
             When the domain part is an IPv4 address.
         simple_host:
@@ -67,7 +69,12 @@ def email(
     if ipv6_address or ipv4_address:
         if domain_part.startswith("[") and domain_part.endswith("]"):
             # ref: RFC 5321
-            domain_part = domain_part.lstrip("[").rstrip("]")
+            if domain_part[1:6].lower() == "ipv6:":
+                domain_part = domain_part[6:-1]
+                if not ipv6_address or "%" in domain_part or not ipv6(domain_part, cidr=False):
+                    return False
+            else:
+                domain_part = domain_part.lstrip("[").rstrip("]")
         else:
             return False
 

tests/test_email.py

@@ -72,3 +72,39 @@ def test_rejects_newline_after_local_part(local_part: str):
 def test_returns_failed_validation_on_idna_mapped_lookalike_domain(domain_part: str):
     """Test returns failed validation on email domains that only IDNA 2003 mapping makes valid."""
     assert isinstance(email(f"user@{domain_part}"), ValidationError)
+
+
+@pytest.mark.parametrize(
+    "address",
+    ["2001:db8::1", "2001:db8:0:0:0:0:0:1", "::ffff:192.0.2.1"],
+)
+def test_accepts_tagged_ipv6_literal(address: str):
+    """Accept RFC 5321 address literals when IPv6 addresses are enabled."""
+    assert email(f"user@[IPv6:{address}]", ipv6_address=True) is True
+    assert email(f"user@[ipv6:{address}]", ipv6_address=True) is True
+    assert isinstance(email(f"user@[IPv6:{address}]"), ValidationError)
+    assert isinstance(email(f"user@[IPv6:{address}]", ipv4_address=True), ValidationError)
+
+
+@pytest.mark.parametrize(
+    "address", ["", "example.com", "192.0.2.1", "2001:db8::xyz", "fe80::1%eth0"]
+)
+def test_rejects_invalid_tagged_ipv6_literal(address: str):
+    """An IPv6 tag must identify a valid IPv6 address, never a hostname or IPv4."""
+    assert isinstance(email(f"user@[IPv6:{address}]", ipv6_address=True), ValidationError)
+    assert isinstance(
+        email(f"user@[IPv6:{address}]", ipv6_address=True, ipv4_address=True), ValidationError
+    )
+
+
+def test_rejects_extra_brackets_around_tagged_ipv6_literal():
+    """Do not strip repeated brackets while interpreting an IPv6 tag."""
+    assert isinstance(email("user@[[IPv6:2001:db8::1]]", ipv6_address=True), ValidationError)
+
+
+def test_preserves_legacy_email_address_literals():
+    """Keep bare IPv6 and IPv4 literal support compatible."""
+    assert email("user@[2001:db8::1]", ipv6_address=True) is True
+    assert email("user@[192.0.2.1]", ipv4_address=True) is True
+    assert email("user@[IPv6:2001:db8::1]", ipv6_address=True, ipv4_address=True) is True
+    assert isinstance(email("invalid local@[IPv6:2001:db8::1]", ipv6_address=True), ValidationError)