Change special use domain names to raise EmailSyntaxError instead of EmailUndeliverableError

This way all DNS-based checks raise EmailUndeliverableError and all non-DNS-based checks raise EmailSyntaxError.

This was suggested by someone in GitHub issues although I can't find that anymore.

Author: JoshData

README.md

@@ -165,7 +165,7 @@ while True:
 
 ### Test addresses
 
-This library rejects email addresess that use the [Special Use Domain Names](https://www.iana.org/assignments/special-use-domain-names/special-use-domain-names.xhtml) `invalid`, `localhost`, `test`, and some others by raising `EmailUndeliverableError`. This is to protect your system from abuse: You probably don't want a user to be able to cause an email to be sent to `localhost`. However, in your non-production test environments you may want to use `@test` or `@myname.test` email addresses. There are three ways you can allow this:
+This library rejects email addresess that use the [Special Use Domain Names](https://www.iana.org/assignments/special-use-domain-names/special-use-domain-names.xhtml) `invalid`, `localhost`, `test`, and some others by raising `EmailSyntaxError`. This is to protect your system from abuse: You probably don't want a user to be able to cause an email to be sent to `localhost`. However, in your non-production test environments you may want to use `@test` or `@myname.test` email addresses. There are three ways you can allow this:
 
 1. Add `test_environment=True` to the call to `validate_email` (see above).
 2. Set `email_validator.TEST_ENVIRONMENT` to `True`.
@@ -409,11 +409,9 @@ or likely to cause trouble:
   (without NULL MX or SPF -all DNS records) if deliverability
   checks are turned on.
   Most [Special Use Domain Names](https://www.iana.org/assignments/special-use-domain-names/special-use-domain-names.xhtml)
-  and their subdomains are considered invalid (except see
-  the `test_environment` parameter above), if deliverability checks are
-  turned on. Domain names without a `.` are rejected as a syntax error
-  since no one has an email address directly at a TLD, and a missing
-  TLD is a common user error.
+  and their subdomains and
+  domain names without a `.` are rejected as a syntax error
+  (except see the `test_environment` parameter above).
 * Obsolete email syntaxes are rejected:
   The "quoted string" form of the local part of the email address (RFC
   5321 4.1.2) is not permitted.

email_validator/__init__.py

@@ -559,8 +559,7 @@ def validate_email_domain_part(domain, test_environment=False):
     if "." not in ascii_domain and not (ascii_domain == "test" and test_environment):
         raise EmailSyntaxError("The domain name %s is not valid. It should have a period." % domain_i18n)
 
-    # Check special-use and reserved domain names. Raise these as
-    # deliverability errors since they are syntactically valid.
+    # Check special-use and reserved domain names.
     # Some might fail DNS-based deliverability checks, but that
     # can be turned off, so we should fail them all sooner.
     for d in SPECIAL_USE_DOMAIN_NAMES:
@@ -569,12 +568,11 @@ def validate_email_domain_part(domain, test_environment=False):
             continue
 
         if ascii_domain == d or ascii_domain.endswith("." + d):
-            raise EmailUndeliverableError("The domain name %s is a special-use or reserved name that cannot be used with email." % domain_i18n)
+            raise EmailSyntaxError("The domain name %s is a special-use or reserved name that cannot be used with email." % domain_i18n)
 
-    # We also know that all TLDs currently end with a letter, and
-    # we'll consider that a non-DNS based deliverability check.
+    # We also know that all TLDs currently end with a letter.
     if not re.search(r"[A-Za-z]\Z", ascii_domain):
-        raise EmailUndeliverableError(
+        raise EmailSyntaxError(
             "The domain name %s is not valid. It is not within a valid top-level domain." % domain_i18n
         )
 

tests/test_main.py

@@ -271,7 +271,7 @@ def test_email_invalid_syntax(email_input, error_msg):
 def test_email_invalid_reserved_domain(email_input):
     # Since these all fail deliverabiltiy from a static list,
     # DNS deliverability checks do not arise.
-    with pytest.raises(EmailUndeliverableError) as exc_info:
+    with pytest.raises(EmailSyntaxError) as exc_info:
         validate_email(email_input)
     # print(f'({email_input!r}, {str(exc_info.value)!r}),')
     assert "is a special-use or reserved name" in str(exc_info.value)