diff --git a/.github/workflows/test_and_build.yaml b/.github/workflows/test_and_build.yaml
index 5268a2b..6cc4a07 100644
--- a/.github/workflows/test_and_build.yaml
+++ b/.github/workflows/test_and_build.yaml
@@ -1,6 +1,6 @@
 name: Tests
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:
diff --git a/email_validator/__init__.py b/email_validator/__init__.py
index 3f10088..626aa00 100644
--- a/email_validator/__init__.py
+++ b/email_validator/__init__.py
@@ -1,3 +1,5 @@
+from typing import TYPE_CHECKING
+
 # Export the main method, helper methods, and the public data types.
 from .exceptions_types import ValidatedEmail, EmailNotValidError, \
                               EmailSyntaxError, EmailUndeliverableError
@@ -9,12 +11,14 @@
            "EmailSyntaxError", "EmailUndeliverableError",
            "caching_resolver", "__version__"]
 
-
-def caching_resolver(*args, **kwargs):
-    # Lazy load `deliverability` as it is slow to import (due to dns.resolver)
+if TYPE_CHECKING:
     from .deliverability import caching_resolver
+else:
+    def caching_resolver(*args, **kwargs):
+        # Lazy load `deliverability` as it is slow to import (due to dns.resolver)
+        from .deliverability import caching_resolver
 
-    return caching_resolver(*args, **kwargs)
+        return caching_resolver(*args, **kwargs)
 
 
 # These global attributes are a part of the library's API and can be
diff --git a/email_validator/__main__.py b/email_validator/__main__.py
index a414ff6..52791c7 100644
--- a/email_validator/__main__.py
+++ b/email_validator/__main__.py
@@ -17,17 +17,18 @@
 import json
 import os
 import sys
+from typing import Any, Dict, Optional
 
-from .validate_email import validate_email
+from .validate_email import validate_email, _Resolver
 from .deliverability import caching_resolver
 from .exceptions_types import EmailNotValidError
 
 
-def main(dns_resolver=None):
+def main(dns_resolver: Optional[_Resolver] = None) -> None:
     # The dns_resolver argument is for tests.
 
     # Set options from environment variables.
-    options = {}
+    options: Dict[str, Any] = {}
     for varname in ('ALLOW_SMTPUTF8', 'ALLOW_QUOTED_LOCAL', 'ALLOW_DOMAIN_LITERAL',
                     'GLOBALLY_DELIVERABLE', 'CHECK_DELIVERABILITY', 'TEST_ENVIRONMENT'):
         if varname in os.environ:
diff --git a/email_validator/deliverability.py b/email_validator/deliverability.py
index e2e5076..90f5f9a 100644
--- a/email_validator/deliverability.py
+++ b/email_validator/deliverability.py
@@ -1,4 +1,4 @@
-from typing import Optional, Any, Dict
+from typing import Any, List, Optional, Tuple, TypedDict
 
 import ipaddress
 
@@ -8,17 +8,24 @@
 import dns.exception
 
 
-def caching_resolver(*, timeout: Optional[int] = None, cache=None, dns_resolver=None):
+def caching_resolver(*, timeout: Optional[int] = None, cache: Any = None, dns_resolver: Optional[dns.resolver.Resolver] = None) -> dns.resolver.Resolver:
     if timeout is None:
         from . import DEFAULT_TIMEOUT
         timeout = DEFAULT_TIMEOUT
     resolver = dns_resolver or dns.resolver.Resolver()
-    resolver.cache = cache or dns.resolver.LRUCache()  # type: ignore
-    resolver.lifetime = timeout  # type: ignore # timeout, in seconds
+    resolver.cache = cache or dns.resolver.LRUCache()
+    resolver.lifetime = timeout  # timeout, in seconds
     return resolver
 
 
-def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Optional[int] = None, dns_resolver=None):
+DeliverabilityInfo = TypedDict("DeliverabilityInfo", {
+    "mx": List[Tuple[int, str]],
+    "mx_fallback_type": Optional[str],
+    "unknown-deliverability": str,
+}, total=False)
+
+
+def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Optional[int] = None, dns_resolver: Optional[dns.resolver.Resolver] = None) -> DeliverabilityInfo:
     # Check that the domain resolves to an MX record. If there is no MX record,
     # try an A or AAAA record which is a deprecated fallback for deliverability.
     # Raises an EmailUndeliverableError on failure. On success, returns a dict
@@ -36,7 +43,7 @@ def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Option
     elif timeout is not None:
         raise ValueError("It's not valid to pass both timeout and dns_resolver.")
 
-    deliverability_info: Dict[str, Any] = {}
+    deliverability_info: DeliverabilityInfo = {}
 
     try:
         try:
@@ -69,9 +76,9 @@ def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Option
             # https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
             # https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml
             # (Issue #134.)
-            def is_global_addr(ipaddr):
+            def is_global_addr(address: Any) -> bool:
                 try:
-                    ipaddr = ipaddress.ip_address(ipaddr)
+                    ipaddr = ipaddress.ip_address(address)
                 except ValueError:
                     return False
                 return ipaddr.is_global
@@ -115,7 +122,6 @@ def is_global_addr(ipaddr):
                 for rec in response:
                     value = b"".join(rec.strings)
                     if value.startswith(b"v=spf1 "):
-                        deliverability_info["spf"] = value.decode("ascii", errors='replace')
                         if value == b"v=spf1 -all":
                             raise EmailUndeliverableError(f"The domain name {domain_i18n} does not send email.")
             except dns.resolver.NoAnswer:
diff --git a/email_validator/exceptions_types.py b/email_validator/exceptions_types.py
index 7483b0b..928a94f 100644
--- a/email_validator/exceptions_types.py
+++ b/email_validator/exceptions_types.py
@@ -1,5 +1,5 @@
 import warnings
-from typing import Optional
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 
 class EmailNotValidError(ValueError):
@@ -24,7 +24,7 @@ class ValidatedEmail:
     """The email address that was passed to validate_email. (If passed as bytes, this will be a string.)"""
     original: str
 
-    """The normalized email address, which should always be used in preferance to the original address.
+    """The normalized email address, which should always be used in preference to the original address.
     The normalized address converts an IDNA ASCII domain name to Unicode, if possible, and performs
     Unicode normalization on the local part and on the domain (if originally Unicode). It is the
     concatenation of the local_part and domain attributes, separated by an @-sign."""
@@ -56,25 +56,20 @@ class ValidatedEmail:
 
     """If a deliverability check is performed and if it succeeds, a list of (priority, domain)
     tuples of MX records specified in the DNS for the domain."""
-    mx: list
+    mx: List[Tuple[int, str]]
 
     """If no MX records are actually specified in DNS and instead are inferred, through an obsolete
     mechanism, from A or AAAA records, the value is the type of DNS record used instead (`A` or `AAAA`)."""
-    mx_fallback_type: str
+    mx_fallback_type: Optional[str]
 
     """The display name in the original input text, unquoted and unescaped, or None."""
-    display_name: str
+    display_name: Optional[str]
 
-    """Tests use this constructor."""
-    def __init__(self, **kwargs):
-        for k, v in kwargs.items():
-            setattr(self, k, v)
-
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"<ValidatedEmail {self.normalized}>"
 
     """For backwards compatibility, support old field names."""
-    def __getattr__(self, key):
+    def __getattr__(self, key: str) -> str:
         if key == "original_email":
             return self.original
         if key == "email":
@@ -82,13 +77,13 @@ def __getattr__(self, key):
         raise AttributeError(key)
 
     @property
-    def email(self):
+    def email(self) -> str:
         warnings.warn("ValidatedEmail.email is deprecated and will be removed, use ValidatedEmail.normalized instead", DeprecationWarning)
         return self.normalized
 
     """For backwards compatibility, some fields are also exposed through a dict-like interface. Note
     that some of the names changed when they became attributes."""
-    def __getitem__(self, key):
+    def __getitem__(self, key: str) -> Union[Optional[str], bool, List[Tuple[int, str]]]:
         warnings.warn("dict-like access to the return value of validate_email is deprecated and may not be supported in the future.", DeprecationWarning, stacklevel=2)
         if key == "email":
             return self.normalized
@@ -109,7 +104,7 @@ def __getitem__(self, key):
         raise KeyError()
 
     """Tests use this."""
-    def __eq__(self, other):
+    def __eq__(self, other: object) -> bool:
         if not isinstance(other, ValidatedEmail):
             return False
         return (
@@ -127,7 +122,7 @@ def __eq__(self, other):
         )
 
     """This helps producing the README."""
-    def as_constructor(self):
+    def as_constructor(self) -> str:
         return "ValidatedEmail(" \
             + ",".join(f"\n  {key}={repr(getattr(self, key))}"
                        for key in ('normalized', 'local_part', 'domain',
@@ -139,7 +134,7 @@ def as_constructor(self):
             + ")"
 
     """Convenience method for accessing ValidatedEmail as a dict"""
-    def as_dict(self):
+    def as_dict(self) -> Dict[str, Any]:
         d = self.__dict__
         if d.get('domain_address'):
             d['domain_address'] = repr(d['domain_address'])
diff --git a/email_validator/syntax.py b/email_validator/syntax.py
index b8df0e6..efbcd73 100644
--- a/email_validator/syntax.py
+++ b/email_validator/syntax.py
@@ -1,4 +1,4 @@
-from .exceptions_types import EmailSyntaxError
+from .exceptions_types import EmailSyntaxError, ValidatedEmail
 from .rfc_constants import EMAIL_MAX_LENGTH, LOCAL_PART_MAX_LENGTH, DOMAIN_MAX_LENGTH, \
     DOT_ATOM_TEXT, DOT_ATOM_TEXT_INTL, ATEXT_RE, ATEXT_INTL_DOT_RE, ATEXT_HOSTNAME_INTL, QTEXT_INTL, \
     DNS_LABEL_LENGTH_LIMIT, DOT_ATOM_TEXT_HOSTNAME, DOMAIN_NAME_REGEX, DOMAIN_LITERAL_CHARS
@@ -7,10 +7,10 @@
 import unicodedata
 import idna  # implements IDNA 2008; Python's codec is only IDNA 2003
 import ipaddress
-from typing import Optional
+from typing import Optional, Tuple, TypedDict, Union
 
 
-def split_email(email):
+def split_email(email: str) -> Tuple[Optional[str], str, str, bool]:
     # Return the display name, unescaped local part, and domain part
     # of the address, and whether the local part was quoted. If no
     # display name was present and angle brackets do not surround
@@ -46,7 +46,7 @@ def split_email(email):
     # We assume the input string is already stripped of leading and
     # trailing CFWS.
 
-    def split_string_at_unquoted_special(text, specials):
+    def split_string_at_unquoted_special(text: str, specials: Tuple[str, ...]) -> Tuple[str, str]:
         # Split the string at the first character in specials (an @-sign
         # or left angle bracket) that does not occur within quotes.
         inside_quote = False
@@ -77,7 +77,7 @@ def split_string_at_unquoted_special(text, specials):
 
         return left_part, right_part
 
-    def unquote_quoted_string(text):
+    def unquote_quoted_string(text: str) -> Tuple[str, bool]:
         # Remove surrounding quotes and unescape escaped backslashes
         # and quotes. Escapes are parsed liberally. I think only
         # backslashes and quotes can be escaped but we'll allow anything
@@ -155,7 +155,7 @@ def unquote_quoted_string(text):
     return display_name, local_part, domain_part, is_quoted_local_part
 
 
-def get_length_reason(addr, utf8=False, limit=EMAIL_MAX_LENGTH):
+def get_length_reason(addr: str, utf8: bool = False, limit: int = EMAIL_MAX_LENGTH) -> str:
     """Helper function to return an error message related to invalid length."""
     diff = len(addr) - limit
     prefix = "at least " if utf8 else ""
@@ -163,7 +163,7 @@ def get_length_reason(addr, utf8=False, limit=EMAIL_MAX_LENGTH):
     return f"({prefix}{diff} character{suffix} too many)"
 
 
-def safe_character_display(c):
+def safe_character_display(c: str) -> str:
     # Return safely displayable characters in quotes.
     if c == '\\':
         return f"\"{c}\""  # can't use repr because it escapes it
@@ -180,8 +180,14 @@ def safe_character_display(c):
     return unicodedata.name(c, h)
 
 
+class LocalPartValidationResult(TypedDict):
+    local_part: str
+    ascii_local_part: Optional[str]
+    smtputf8: bool
+
+
 def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_empty_local: bool = False,
-                              quoted_local_part: bool = False):
+                              quoted_local_part: bool = False) -> LocalPartValidationResult:
     """Validates the syntax of the local part of an email address."""
 
     if len(local) == 0:
@@ -345,7 +351,7 @@ def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_emp
     raise EmailSyntaxError("The email address contains invalid characters before the @-sign.")
 
 
-def check_unsafe_chars(s, allow_space=False):
+def check_unsafe_chars(s: str, allow_space: bool = False) -> None:
     # Check for unsafe characters or characters that would make the string
     # invalid or non-sensible Unicode.
     bad_chars = set()
@@ -397,7 +403,7 @@ def check_unsafe_chars(s, allow_space=False):
                                + ", ".join(safe_character_display(c) for c in sorted(bad_chars)) + ".")
 
 
-def check_dot_atom(label, start_descr, end_descr, is_hostname):
+def check_dot_atom(label: str, start_descr: str, end_descr: str, is_hostname: bool) -> None:
     # RFC 5322 3.2.3
     if label.endswith("."):
         raise EmailSyntaxError(end_descr.format("period"))
@@ -416,7 +422,12 @@ def check_dot_atom(label, start_descr, end_descr, is_hostname):
             raise EmailSyntaxError("An email address cannot have a period and a hyphen next to each other.")
 
 
-def validate_email_domain_name(domain, test_environment=False, globally_deliverable=True):
+class DomainNameValidationResult(TypedDict):
+    ascii_domain: str
+    domain: str
+
+
+def validate_email_domain_name(domain: str, test_environment: bool = False, globally_deliverable: bool = True) -> DomainNameValidationResult:
     """Validates the syntax of the domain part of an email address."""
 
     # Check for invalid characters before normalization.
@@ -580,7 +591,7 @@ def validate_email_domain_name(domain, test_environment=False, globally_delivera
     }
 
 
-def validate_email_length(addrinfo):
+def validate_email_length(addrinfo: ValidatedEmail) -> None:
     # If the email address has an ASCII representation, then we assume it may be
     # transmitted in ASCII (we can't assume SMTPUTF8 will be used on all hops to
     # the destination) and the length limit applies to ASCII characters (which is
@@ -621,11 +632,18 @@ def validate_email_length(addrinfo):
         raise EmailSyntaxError(f"The email address is too long {reason}.")
 
 
-def validate_email_domain_literal(domain_literal):
+class DomainLiteralValidationResult(TypedDict):
+    domain_address: Union[ipaddress.IPv4Address, ipaddress.IPv6Address]
+    domain: str
+
+
+def validate_email_domain_literal(domain_literal: str) -> DomainLiteralValidationResult:
     # This is obscure domain-literal syntax. Parse it and return
     # a compressed/normalized address.
     # RFC 5321 4.1.3 and RFC 5322 3.4.1.
 
+    addr: Union[ipaddress.IPv4Address, ipaddress.IPv6Address]
+
     # Try to parse the domain literal as an IPv4 address.
     # There is no tag for IPv4 addresses, so we can never
     # be sure if the user intends an IPv4 address.
diff --git a/email_validator/validate_email.py b/email_validator/validate_email.py
index f73a479..2adda2a 100644
--- a/email_validator/validate_email.py
+++ b/email_validator/validate_email.py
@@ -1,9 +1,15 @@
-from typing import Optional, Union
+from typing import Optional, Union, TYPE_CHECKING
 
 from .exceptions_types import EmailSyntaxError, ValidatedEmail
 from .syntax import split_email, validate_email_local_part, validate_email_domain_name, validate_email_domain_literal, validate_email_length
 from .rfc_constants import CASE_INSENSITIVE_MAILBOX_NAMES
 
+if TYPE_CHECKING:
+    import dns.resolver
+    _Resolver = dns.resolver.Resolver
+else:
+    _Resolver = object
+
 
 def validate_email(
     email: Union[str, bytes],
@@ -18,7 +24,7 @@ def validate_email(
     test_environment: Optional[bool] = None,
     globally_deliverable: Optional[bool] = None,
     timeout: Optional[int] = None,
-    dns_resolver: Optional[object] = None
+    dns_resolver: Optional[_Resolver] = None
 ) -> ValidatedEmail:
     """
     Given an email address, and some options, returns a ValidatedEmail instance
@@ -104,20 +110,20 @@ def validate_email(
 
     elif domain_part.startswith("[") and domain_part.endswith("]"):
         # Parse the address in the domain literal and get back a normalized domain.
-        domain_part_info = validate_email_domain_literal(domain_part[1:-1])
+        domain_literal_info = validate_email_domain_literal(domain_part[1:-1])
         if not allow_domain_literal:
             raise EmailSyntaxError("A bracketed IP address after the @-sign is not allowed here.")
-        ret.domain = domain_part_info["domain"]
-        ret.ascii_domain = domain_part_info["domain"]  # Domain literals are always ASCII.
-        ret.domain_address = domain_part_info["domain_address"]
+        ret.domain = domain_literal_info["domain"]
+        ret.ascii_domain = domain_literal_info["domain"]  # Domain literals are always ASCII.
+        ret.domain_address = domain_literal_info["domain_address"]
         is_domain_literal = True  # Prevent deliverability checks.
 
     else:
         # Check the syntax of the domain and get back a normalized
         # internationalized and ASCII form.
-        domain_part_info = validate_email_domain_name(domain_part, test_environment=test_environment, globally_deliverable=globally_deliverable)
-        ret.domain = domain_part_info["domain"]
-        ret.ascii_domain = domain_part_info["ascii_domain"]
+        domain_name_info = validate_email_domain_name(domain_part, test_environment=test_environment, globally_deliverable=globally_deliverable)
+        ret.domain = domain_name_info["domain"]
+        ret.ascii_domain = domain_name_info["ascii_domain"]
 
     # Construct the complete normalized form.
     ret.normalized = ret.local_part + "@" + ret.domain
@@ -146,7 +152,9 @@ def validate_email(
         deliverability_info = validate_email_deliverability(
             ret.ascii_domain, ret.domain, timeout, dns_resolver
         )
-        for key, value in deliverability_info.items():
-            setattr(ret, key, value)
+        mx = deliverability_info.get("mx")
+        if mx is not None:
+            ret.mx = mx
+        ret.mx_fallback_type = deliverability_info.get("mx_fallback_type")
 
     return ret
diff --git a/pyproject.toml b/pyproject.toml
index 1379d17..a92c08e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,16 @@
+[tool.mypy]
+disallow_any_generics = true
+disallow_subclassing_any = true
+
+check_untyped_defs = true
+disallow_incomplete_defs = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
+disallow_untyped_defs = true
+
+warn_redundant_casts = true
+warn_unused_ignores = true
+
 [tool.pytest.ini_options]
 markers = [
     "network: marks tests as requiring Internet access",
diff --git a/tests/mocked_dns_response.py b/tests/mocked_dns_response.py
index 1c7d157..c6db5cb 100644
--- a/tests/mocked_dns_response.py
+++ b/tests/mocked_dns_response.py
@@ -1,3 +1,7 @@
+from typing import Any, Dict, Iterator, Optional
+
+import dns.exception
+import dns.rdataset
 import dns.resolver
 import json
 import os.path
@@ -20,9 +24,11 @@
 class MockedDnsResponseData:
     DATA_PATH = os.path.dirname(__file__) + "/mocked-dns-answers.json"
 
+    INSTANCE = None
+
     @staticmethod
-    def create_resolver():
-        if not hasattr(MockedDnsResponseData, 'INSTANCE'):
+    def create_resolver() -> dns.resolver.Resolver:
+        if MockedDnsResponseData.INSTANCE is None:
             # Create a singleton instance of this class and load the saved DNS responses.
             # Except when BUILD_MOCKED_DNS_RESPONSE_DATA is true, don't load the data.
             singleton = MockedDnsResponseData()
@@ -35,20 +41,19 @@ def create_resolver():
         dns_resolver = dns.resolver.Resolver(configure=BUILD_MOCKED_DNS_RESPONSE_DATA)
         return caching_resolver(cache=MockedDnsResponseData.INSTANCE, dns_resolver=dns_resolver)
 
-    def __init__(self):
-        self.data = {}
+    def __init__(self) -> None:
+        self.data: Dict[dns.resolver.CacheKey, Optional[MockedDnsResponseData.Ans]] = {}
 
-    def load(self):
-        # Loads the saved DNS response data from the JSON file and
-        # re-structures it into dnspython classes.
-        class Ans:  # mocks the dns.resolver.Answer class
+    # Loads the saved DNS response data from the JSON file and
+    # re-structures it into dnspython classes.
+    class Ans:  # mocks the dns.resolver.Answer class
+        def __init__(self, rrset: dns.rdataset.Rdataset) -> None:
+            self.rrset = rrset
 
-            def __init__(self, rrset):
-                self.rrset = rrset
-
-            def __iter__(self):
-                return iter(self.rrset)
+        def __iter__(self) -> Iterator[Any]:
+            return iter(self.rrset)
 
+    def load(self) -> None:
         with open(self.DATA_PATH) as f:
             data = json.load(f)
             for item in data:
@@ -60,11 +65,11 @@ def __iter__(self):
                     for rr in item["answer"]
                 ]
                 if item["answer"]:
-                    self.data[key] = Ans(dns.rdataset.from_rdata_list(0, rdatas=rdatas))
+                    self.data[key] = MockedDnsResponseData.Ans(dns.rdataset.from_rdata_list(0, rdatas=rdatas))
                 else:
                     self.data[key] = None
 
-    def save(self):
+    def save(self) -> None:
         # Re-structure as a list with basic data types.
         data = [
             {
@@ -79,14 +84,15 @@ def save(self):
                 ])
             }
             for key, value in self.data.items()
+            if value is not None
         ]
         with open(self.DATA_PATH, "w") as f:
             json.dump(data, f, indent=True)
 
-    def get(self, key):
+    def get(self, key: dns.resolver.CacheKey) -> Optional[Ans]:
         # Special-case a domain to create a timeout.
         if key[0].to_text() == "timeout.com.":
-            raise dns.exception.Timeout()
+            raise dns.exception.Timeout()  # type: ignore [no-untyped-call]
 
         # When building the DNS response database, return
         # a cache miss.
@@ -96,17 +102,17 @@ def get(self, key):
         # Query the data for a matching record.
         if key in self.data:
             if not self.data[key]:
-                raise dns.resolver.NoAnswer()
+                raise dns.resolver.NoAnswer()  # type: ignore [no-untyped-call]
             return self.data[key]
 
         # Query the data for a response to an ANY query.
         ANY = dns.rdatatype.from_text("ANY")
         if (key[0], ANY, key[2]) in self.data and self.data[(key[0], ANY, key[2])] is None:
-            raise dns.resolver.NXDOMAIN()
+            raise dns.resolver.NXDOMAIN()  # type: ignore [no-untyped-call]
 
         raise ValueError(f"Saved DNS data did not contain query: {key}")
 
-    def put(self, key, value):
+    def put(self, key: dns.resolver.CacheKey, value: Ans) -> None:
         # Build the DNS data by saving the live query response.
         if not BUILD_MOCKED_DNS_RESPONSE_DATA:
             raise ValueError("Should not get here.")
@@ -114,8 +120,8 @@ def put(self, key, value):
 
 
 @pytest.fixture(scope="session", autouse=True)
-def MockedDnsResponseDataCleanup(request):
-    def cleanup_func():
-        if BUILD_MOCKED_DNS_RESPONSE_DATA:
+def MockedDnsResponseDataCleanup(request: pytest.FixtureRequest) -> None:
+    def cleanup_func() -> None:
+        if BUILD_MOCKED_DNS_RESPONSE_DATA and MockedDnsResponseData.INSTANCE is not None:
             MockedDnsResponseData.INSTANCE.save()
     request.addfinalizer(cleanup_func)
diff --git a/tests/test_deliverability.py b/tests/test_deliverability.py
index 0ed5c3f..b65116b 100644
--- a/tests/test_deliverability.py
+++ b/tests/test_deliverability.py
@@ -1,3 +1,5 @@
+from typing import Any, Dict
+
 import pytest
 import re
 
@@ -17,7 +19,7 @@
         ('pages.github.com', {'mx': [(0, 'pages.github.com')], 'mx_fallback_type': 'A'}),
     ],
 )
-def test_deliverability_found(domain, expected_response):
+def test_deliverability_found(domain: str, expected_response: str) -> None:
     response = validate_email_deliverability(domain, domain, dns_resolver=RESOLVER)
     assert response == expected_response
 
@@ -35,7 +37,7 @@ def test_deliverability_found(domain, expected_response):
         ('justtxt.joshdata.me', 'The domain name {domain} does not accept email'),
     ],
 )
-def test_deliverability_fails(domain, error):
+def test_deliverability_fails(domain: str, error: str) -> None:
     with pytest.raises(EmailUndeliverableError, match=error.format(domain=domain)):
         validate_email_deliverability(domain, domain, dns_resolver=RESOLVER)
 
@@ -48,7 +50,7 @@ def test_deliverability_fails(domain, error):
         ('me@mail.example.com'),
     ],
 )
-def test_email_example_reserved_domain(email_input):
+def test_email_example_reserved_domain(email_input: str) -> None:
     # Since these all fail deliverabiltiy from a static list,
     # DNS deliverability checks do not arise.
     with pytest.raises(EmailUndeliverableError) as exc_info:
@@ -57,22 +59,22 @@ def test_email_example_reserved_domain(email_input):
     assert re.match(r"The domain name [a-z\.]+ does not (accept email|exist)\.", str(exc_info.value)) is not None
 
 
-def test_deliverability_dns_timeout():
+def test_deliverability_dns_timeout() -> None:
     response = validate_email_deliverability('timeout.com', 'timeout.com', dns_resolver=RESOLVER)
     assert "mx" not in response
     assert response.get("unknown-deliverability") == "timeout"
 
 
 @pytest.mark.network
-def test_caching_dns_resolver():
+def test_caching_dns_resolver() -> None:
     class TestCache:
-        def __init__(self):
-            self.cache = {}
+        def __init__(self) -> None:
+            self.cache: Dict[Any, Any] = {}
 
-        def get(self, key):
+        def get(self, key: Any) -> Any:
             return self.cache.get(key)
 
-        def put(self, key, value):
+        def put(self, key: Any, value: Any) -> Any:
             self.cache[key] = value
 
     cache = TestCache()
diff --git a/tests/test_main.py b/tests/test_main.py
index 579163f..ab8eecd 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -9,14 +9,14 @@
 RESOLVER = MockedDnsResponseData.create_resolver()
 
 
-def test_dict_accessor():
+def test_dict_accessor() -> None:
     input_email = "testaddr@example.tld"
     valid_email = validate_email(input_email, check_deliverability=False)
     assert isinstance(valid_email.as_dict(), dict)
     assert valid_email.as_dict()["original"] == input_email
 
 
-def test_main_single_good_input(monkeypatch, capsys):
+def test_main_single_good_input(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
     import json
     test_email = "google@google.com"
     monkeypatch.setattr('sys.argv', ['email_validator', test_email])
@@ -27,7 +27,7 @@ def test_main_single_good_input(monkeypatch, capsys):
     assert validate_email(test_email, dns_resolver=RESOLVER).original == output["original"]
 
 
-def test_main_single_bad_input(monkeypatch, capsys):
+def test_main_single_bad_input(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
     bad_email = 'test@..com'
     monkeypatch.setattr('sys.argv', ['email_validator', bad_email])
     validator_command_line_tool(dns_resolver=RESOLVER)
@@ -35,7 +35,7 @@ def test_main_single_bad_input(monkeypatch, capsys):
     assert stdout == 'An email address cannot have a period immediately after the @-sign.\n'
 
 
-def test_main_multi_input(monkeypatch, capsys):
+def test_main_multi_input(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
     import io
     test_cases = ["google1@google.com", "google2@google.com", "test@.com", "test3@.com"]
     test_input = io.StringIO("\n".join(test_cases))
@@ -49,7 +49,7 @@ def test_main_multi_input(monkeypatch, capsys):
     assert test_cases[3] in stdout
 
 
-def test_bytes_input():
+def test_bytes_input() -> None:
     input_email = b"testaddr@example.tld"
     valid_email = validate_email(input_email, check_deliverability=False)
     assert isinstance(valid_email.as_dict(), dict)
@@ -60,7 +60,7 @@ def test_bytes_input():
         validate_email(input_email, check_deliverability=False)
 
 
-def test_deprecation():
+def test_deprecation() -> None:
     input_email = b"testaddr@example.tld"
     valid_email = validate_email(input_email, check_deliverability=False)
     with pytest.deprecated_call():
diff --git a/tests/test_syntax.py b/tests/test_syntax.py
index 65e3ec0..de41253 100644
--- a/tests/test_syntax.py
+++ b/tests/test_syntax.py
@@ -1,3 +1,5 @@
+from typing import Any
+
 import pytest
 
 from email_validator import EmailSyntaxError, \
@@ -5,12 +7,19 @@
                             ValidatedEmail
 
 
+def MakeValidatedEmail(**kwargs: Any) -> ValidatedEmail:
+    ret = ValidatedEmail()
+    for k, v in kwargs.items():
+        setattr(ret, k, v)
+    return ret
+
+
 @pytest.mark.parametrize(
     'email_input,output',
     [
         (
             'Abc@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='Abc',
                 ascii_local_part='Abc',
                 smtputf8=False,
@@ -22,7 +31,7 @@
         ),
         (
             'Abc.123@test-example.com',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='Abc.123',
                 ascii_local_part='Abc.123',
                 smtputf8=False,
@@ -34,7 +43,7 @@
         ),
         (
             'user+mailbox/department=shipping@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='user+mailbox/department=shipping',
                 ascii_local_part='user+mailbox/department=shipping',
                 smtputf8=False,
@@ -46,7 +55,7 @@
         ),
         (
             "!#$%&'*+-/=?^_`.{|}~@example.tld",
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part="!#$%&'*+-/=?^_`.{|}~",
                 ascii_local_part="!#$%&'*+-/=?^_`.{|}~",
                 smtputf8=False,
@@ -58,7 +67,7 @@
         ),
         (
             'jeff@臺網中心.tw',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='jeff',
                 ascii_local_part='jeff',
                 smtputf8=False,
@@ -70,7 +79,7 @@
         ),
         (
             '"quoted local part"@example.org',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='"quoted local part"',
                 ascii_local_part='"quoted local part"',
                 smtputf8=False,
@@ -82,7 +91,7 @@
         ),
         (
             '"de-quoted.local.part"@example.org',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='de-quoted.local.part',
                 ascii_local_part='de-quoted.local.part',
                 smtputf8=False,
@@ -94,7 +103,7 @@
         ),
         (
             'MyName <me@example.org>',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='me',
                 ascii_local_part='me',
                 smtputf8=False,
@@ -107,7 +116,7 @@
         ),
         (
             'My Name <me@example.org>',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='me',
                 ascii_local_part='me',
                 smtputf8=False,
@@ -120,7 +129,7 @@
         ),
         (
             r'"My.\"Na\\me\".Is" <"me \" \\ me"@example.org>',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part=r'"me \" \\ me"',
                 ascii_local_part=r'"me \" \\ me"',
                 smtputf8=False,
@@ -133,7 +142,7 @@
         ),
     ],
 )
-def test_email_valid(email_input, output):
+def test_email_valid(email_input: str, output: ValidatedEmail) -> None:
     # These addresses do not require SMTPUTF8. See test_email_valid_intl_local_part
     # for addresses that are valid but require SMTPUTF8. Check that it passes with
     # allow_smtput8 both on and off.
@@ -157,7 +166,7 @@ def test_email_valid(email_input, output):
     [
         (
             '伊昭傑@郵件.商務',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='伊昭傑',
                 smtputf8=True,
                 ascii_domain='xn--5nqv22n.xn--lhr59c',
@@ -167,7 +176,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'राम@मोहन.ईन्फो',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='राम',
                 smtputf8=True,
                 ascii_domain='xn--l2bl7a9d.xn--o1b8dj2ki',
@@ -177,7 +186,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'юзер@екзампл.ком',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='юзер',
                 smtputf8=True,
                 ascii_domain='xn--80ajglhfv.xn--j1aef',
@@ -187,7 +196,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'θσερ@εχαμπλε.ψομ',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='θσερ',
                 smtputf8=True,
                 ascii_domain='xn--mxahbxey0c.xn--xxaf0a',
@@ -197,7 +206,7 @@ def test_email_valid(email_input, output):
         ),
         (
             '葉士豪@臺網中心.tw',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='葉士豪',
                 smtputf8=True,
                 ascii_domain='xn--fiqq24b10vi0d.tw',
@@ -207,7 +216,7 @@ def test_email_valid(email_input, output):
         ),
         (
             '葉士豪@臺網中心.台灣',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='葉士豪',
                 smtputf8=True,
                 ascii_domain='xn--fiqq24b10vi0d.xn--kpry57d',
@@ -217,7 +226,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'jeff葉@臺網中心.tw',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='jeff葉',
                 smtputf8=True,
                 ascii_domain='xn--fiqq24b10vi0d.tw',
@@ -227,7 +236,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'ñoñó@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='ñoñó',
                 smtputf8=True,
                 ascii_domain='example.tld',
@@ -237,7 +246,7 @@ def test_email_valid(email_input, output):
         ),
         (
             '我買@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='我買',
                 smtputf8=True,
                 ascii_domain='example.tld',
@@ -247,7 +256,7 @@ def test_email_valid(email_input, output):
         ),
         (
             '甲斐黒川日本@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='甲斐黒川日本',
                 smtputf8=True,
                 ascii_domain='example.tld',
@@ -257,7 +266,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'чебурашкаящик-с-апельсинами.рф@example.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='чебурашкаящик-с-апельсинами.рф',
                 smtputf8=True,
                 ascii_domain='example.tld',
@@ -267,7 +276,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'उदाहरण.परीक्ष@domain.with.idn.tld',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='उदाहरण.परीक्ष',
                 smtputf8=True,
                 ascii_domain='domain.with.idn.tld',
@@ -277,7 +286,7 @@ def test_email_valid(email_input, output):
         ),
         (
             'ιωάννης@εεττ.gr',
-            ValidatedEmail(
+            MakeValidatedEmail(
                 local_part='ιωάννης',
                 smtputf8=True,
                 ascii_domain='xn--qxaa9ba.gr',
@@ -287,7 +296,7 @@ def test_email_valid(email_input, output):
         ),
     ],
 )
-def test_email_valid_intl_local_part(email_input, output):
+def test_email_valid_intl_local_part(email_input: str, output: ValidatedEmail) -> None:
     # Check that it passes when allow_smtputf8 is True.
     assert validate_email(email_input, check_deliverability=False) == output
 
@@ -309,7 +318,7 @@ def test_email_valid_intl_local_part(email_input, output):
         ('"quoted.with..unicode.λ"@example.com', '"quoted.with..unicode.λ"'),
         ('"quoted.with.extraneous.\\escape"@example.com', 'quoted.with.extraneous.escape'),
     ])
-def test_email_valid_only_if_quoted_local_part(email_input, normalized_local_part):
+def test_email_valid_only_if_quoted_local_part(email_input: str, normalized_local_part: str) -> None:
     # These addresses are invalid with the default allow_quoted_local=False option.
     with pytest.raises(EmailSyntaxError) as exc_info:
         validate_email(email_input)
@@ -323,7 +332,7 @@ def test_email_valid_only_if_quoted_local_part(email_input, normalized_local_par
     assert validated.local_part == normalized_local_part
 
 
-def test_domain_literal():
+def test_domain_literal() -> None:
     # Check parsing IPv4 addresses.
     validated = validate_email("me@[127.0.0.1]", allow_domain_literal=True)
     assert validated.domain == "[127.0.0.1]"
@@ -411,7 +420,7 @@ def test_domain_literal():
         ('\"Display.Name\" <me@example.com>', 'A display name and angle brackets around the email address are not permitted here.'),
     ],
 )
-def test_email_invalid_syntax(email_input, error_msg):
+def test_email_invalid_syntax(email_input: str, error_msg: str) -> None:
     # Since these all have syntax errors, deliverability
     # checks do not arise.
     with pytest.raises(EmailSyntaxError) as exc_info:
@@ -430,7 +439,7 @@ def test_email_invalid_syntax(email_input, error_msg):
         ('me@test.test.test'),
     ],
 )
-def test_email_invalid_reserved_domain(email_input):
+def test_email_invalid_reserved_domain(email_input: str) -> None:
     # Since these all fail deliverabiltiy from a static list,
     # DNS deliverability checks do not arise.
     with pytest.raises(EmailSyntaxError) as exc_info:
@@ -454,7 +463,7 @@ def test_email_invalid_reserved_domain(email_input):
         ('\uFDEF', 'U+FDEF'),  # unassigned (Cn)
     ],
 )
-def test_email_unsafe_character(s, expected_error):
+def test_email_unsafe_character(s: str, expected_error: str) -> None:
     # Check for various unsafe characters that are permitted by the email
     # specs but should be disallowed for being unsafe or not sensible Unicode.
 
@@ -474,26 +483,26 @@ def test_email_unsafe_character(s, expected_error):
         ('"quoted.with..unicode.λ"@example.com', 'Internationalized characters before the @-sign are not supported: \'λ\'.'),
     ],
 )
-def test_email_invalid_character_smtputf8_off(email_input, expected_error):
+def test_email_invalid_character_smtputf8_off(email_input: str, expected_error: str) -> None:
     # Check that internationalized characters are rejected if allow_smtputf8=False.
     with pytest.raises(EmailSyntaxError) as exc_info:
         validate_email(email_input, allow_smtputf8=False, test_environment=True)
     assert str(exc_info.value) == expected_error
 
 
-def test_email_empty_local():
+def test_email_empty_local() -> None:
     validate_email("@test", allow_empty_local=True, test_environment=True)
 
     # This next one might not be desirable.
     validate_email("\"\"@test", allow_empty_local=True, allow_quoted_local=True, test_environment=True)
 
 
-def test_email_test_domain_name_in_test_environment():
+def test_email_test_domain_name_in_test_environment() -> None:
     validate_email("anything@test", test_environment=True)
     validate_email("anything@mycompany.test", test_environment=True)
 
 
-def test_case_insensitive_mailbox_name():
+def test_case_insensitive_mailbox_name() -> None:
     validate_email("POSTMASTER@test", test_environment=True).normalized = "postmaster@test"
     validate_email("NOT-POSTMASTER@test", test_environment=True).normalized = "NOT-POSTMASTER@test"
 
@@ -673,7 +682,7 @@ def test_case_insensitive_mailbox_name():
         ['test.(comment)test@iana.org', 'ISEMAIL_DEPREC_COMMENT']
     ]
 )
-def test_pyisemail_tests(email_input, status):
+def test_pyisemail_tests(email_input: str, status: str) -> None:
     if status == "ISEMAIL_VALID":
         # All standard email address forms should not raise an exception
         # with any set of parsing options.