diff --git a/app/errors.py b/app/errors.py
index b951eb16..113b248f 100644
--- a/app/errors.py
+++ b/app/errors.py
@@ -121,3 +121,10 @@ class AccountAlreadyLinkedToAnotherUserException(LinkException):
 class AccountIsUsingAliasAsEmail(LinkException):
     def __init__(self):
         super().__init__("Your account has an alias as it's email address")
+
+
+class ProtonAccountNotVerified(LinkException):
+    def __init__(self):
+        super().__init__(
+            "The Proton account you are trying to use has not been verified"
+        )
diff --git a/app/proton/proton_client.py b/app/proton/proton_client.py
index 9f4beac5..f06325b8 100644
--- a/app/proton/proton_client.py
+++ b/app/proton/proton_client.py
@@ -7,11 +7,12 @@ from typing import Optional
 
 from app.account_linking import SLPlan, SLPlanType
 from app.config import PROTON_EXTRA_HEADER_NAME, PROTON_EXTRA_HEADER_VALUE
+from app.errors import ProtonAccountNotVerified
 from app.log import LOG
 
 _APP_VERSION = "OauthClient_1.0.0"
 
-PROTON_ERROR_CODE_NOT_EXISTS = 2501
+PROTON_ERROR_CODE_HV_NEEDED = 9001
 
 PLAN_FREE = 1
 PLAN_PREMIUM = 2
@@ -57,6 +58,15 @@ def convert_access_token(access_token_response: str) -> AccessCredentials:
     )
 
 
+def handle_response_not_ok(status: int, body: dict, text: str) -> Exception:
+    if status == HTTPStatus.UNPROCESSABLE_ENTITY:
+        res_code = body.get("Code")
+        if res_code == PROTON_ERROR_CODE_HV_NEEDED:
+            return ProtonAccountNotVerified()
+
+    return Exception(f"Unexpected status code. Wanted 200 and got {status}: " + text)
+
+
 class ProtonClient(ABC):
     @abstractmethod
     def get_user(self) -> Optional[UserInformation]:
@@ -124,11 +134,11 @@ class HttpProtonClient(ProtonClient):
     @staticmethod
     def __validate_response(res: Response) -> dict:
         status = res.status_code
-        if status != HTTPStatus.OK:
-            raise Exception(
-                f"Unexpected status code. Wanted 200 and got {status}: " + res.text
-            )
         as_json = res.json()
+        if status != HTTPStatus.OK:
+            raise HttpProtonClient.__handle_response_not_ok(
+                status=status, body=as_json, text=res.text
+            )
         res_code = as_json.get("Code")
         if not res_code or res_code != 1000:
             raise Exception(
diff --git a/tests/proton/test_proton_client.py b/tests/proton/test_proton_client.py
index 3879e760..154cc0af 100644
--- a/tests/proton/test_proton_client.py
+++ b/tests/proton/test_proton_client.py
@@ -1,5 +1,7 @@
 import pytest
+from http import HTTPStatus
 
+from app.errors import ProtonAccountNotVerified
 from app.proton import proton_client
 
 
@@ -19,3 +21,30 @@ def test_convert_access_token_not_containing_invalid_length():
     for case in cases:
         with pytest.raises(Exception):
             proton_client.convert_access_token(case)
+
+
+def test_handle_response_not_ok_account_not_verified():
+    res = proton_client.handle_response_not_ok(
+        status=HTTPStatus.UNPROCESSABLE_ENTITY,
+        body={"Code": proton_client.PROTON_ERROR_CODE_HV_NEEDED},
+        text="",
+    )
+    assert isinstance(res, ProtonAccountNotVerified)
+
+
+def test_handle_response_unprocessable_entity_not_account_not_verified():
+    error_text = "some error text"
+    res = proton_client.handle_response_not_ok(
+        status=HTTPStatus.UNPROCESSABLE_ENTITY, body={"Code": 4567}, text=error_text
+    )
+    assert error_text in res.args[0]
+
+
+def test_handle_response_not_ok_unknown_error():
+    error_text = "some error text"
+    res = proton_client.handle_response_not_ok(
+        status=123,
+        body={"Code": proton_client.PROTON_ERROR_CODE_HV_NEEDED},
+        text=error_text,
+    )
+    assert error_text in res.args[0]