Issue:
Bug: feat(users): Add email domain based restriction for dashboard entry APIs



Currently Zurich uses okta and they use a specific `auth_id` to see the okta login method.

If any user doesn't use `auth_id`, then the user will see the default auth methods that Hyperswitch has and they will be use them to login, which we should restrict for zurich users.

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
There will be a mapping of email domain and auth methods.
This PR will restrict users to enter into the dashboard based on the email domain.


### Additional Changes

- [x] This PR modifies the API contract
- [x] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->
Closes #6939.

## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->
1. Create user auth method with email domain
    ```bash
    curl --location 'http://localhost:8080/user/auth' \
    --header 'Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoiMjAxYTJlZWQtNGE0ZC00MjZlLTg1N2ItMjNhM2ZjZTk5NTMzIiwibWVyY2hhbnRfaWQiOiJtZXJjaGFudF8xNjk3NjIzMjI0Iiwicm9sZV9pZCI6Im1lcmNoYW50X2FkbWluIiwiZXhwIjoxNjk3Nzk2MDI3LCJvcmdfaWQiOiJvcmdfVzJ2NmtPZ2lMSWx3YnFoaVh4VUIifQ.HnkHHWboPt82-VlvE5GVCjTJ1sA82-dMbUxeYNl-mxk' \
    --header 'Content-Type: application/json' \
    --header 'api-key: ••••••' \
    --data '{
        "owner_id": "test",
        "owner_type": "organization",
        "auth_method": {
            "auth_type": "password",
            "private_config": {
                "base_url": "url",
                "client_id": "client_id",
                "client_secret": "client_secret"
            },
            "public_config": {
                "name": "okta"
            }
        },
        "allow_signup": true,
        "email_domain": "gmail.com" 
    }'
    ```
    Response will be 200 OK.

2. Update user auth method
    1. Auth Method
        ```bash
        curl --location --request PUT 'http://localhost:8080/user/auth' \
        --header 'Content-Type: application/json' \
        --header 'api-key: test_admin' \
        --header 'Cookie: Cookie_1=value' \
        --data '{
            "auth_method": {
                "id": "799596e6-e6ba-405c-b5cf-70fd510409dc",
                "auth_method": {
                    "auth_type": "open_id_connect",
                    "private_config": {
                        "base_url": "base url",
                        "client_id": "client id",
                        "client_secret": "client secret"
                    },
                    "public_config": {
                        "name": "okta"
                    }
                }
            }
        }
        '
        ```
        Response will be 200 OK.
    2. Email Domain
         ```bash
          curl --location --request PUT 'http://localhost:8080/user/auth' \
          --header 'Content-Type: application/json' \
          --header 'api-key: test_admin' \
          --header 'Cookie: Cookie_1=value' \
          --data '{
              "email_domain": {
                  "owner_id": "test",
                  "email_domain": "juspay.com"
              }
          }'
          ```
          Response will be 200 OK.

All the following APIs will restrict the users based on the email domain and the corresponding auth method
1. Signin - Password
2. Signup - Password
3. Connect Account - MagicLink
4. Forgot Password - Password
5. Send Verification Email - MagicLink
6. SSO Signin - OpenIdConnect
7. Terminate Auth Select - Selected auth method

If the auth method list for email domain is empty of consists of the above auth method, the request will be continued, or else the api will be stopped.

## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:

1. Create user auth method with email domain
    ```bash
    curl --location 'http://localhost:8080/user/auth' \
    --header 'Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoiMjAxYTJlZWQtNGE0ZC00MjZlLTg1N2ItMjNhM2ZjZTk5NTMzIiwibWVyY2hhbnRfaWQiOiJtZXJjaGFudF8xNjk3NjIzMjI0Iiwicm9sZV9pZCI6Im1lcmNoYW50X2FkbWluIiwiZXhwIjoxNjk3Nzk2MDI3LCJvcmdfaWQiOiJvcmdfVzJ2NmtPZ2lMSWx3YnFoaVh4VUIifQ.HnkHHWboPt82-VlvE5GVCjTJ1sA82-dMbUxeYNl-mxk' \
    --header 'Content-Type: application/json' \
    --header 'api-key: ••••••' \
    --data '{
        "owner_id": "test",
        "owner_type": "organization",
        "auth_method": {
            "auth_type": "password",
            "private_config": {
                "base_url": "url",
                "client_id": "client_id",
                "client_secret": "client_secret"
            },
            "public_config": {
                "name": "okta"
            }
        },
        "allow_signup": true,
        "email_domain": "gmail.com" 
    }'
    ```
    Response will be 200 OK.

2. Update user auth method
    1. Auth Method
        ```bash
        curl --location --request PUT 'http://localhost:8080/user/auth' \
        --header 'Content-Type: application/json' \
        --header 'api-key: test_admin' \
        --header 'Cookie: Cookie_1=value' \
        --data '{
            "auth_method": {
                "id": "799596e6-e6ba-405c-b5cf-70fd510409dc",
                "auth_method": {
                    "auth_type": "open_id_connect",
                    "private_config": {
                        "base_url": "base url",
                        "client_id": "client id",
                        "client_secret": "client secret"
                    },
                    "public_config": {
                        "name": "okta"
                    }
                }
            }
        }
        '
        ```
        Response will be 200 OK.
    2. Email Domain
         ```bash
          curl --location --request PUT 'http://localhost:8080/user/auth' \
          --header 'Content-Type: application/json' \
          --header 'api-key: test_admin' \
          --header 'Cookie: Cookie_1=value' \
          --data '{
              "email_domain": {
                  "owner_id": "test",
                  "email_domain": "juspay.com"
              }
          }'
          ```
          Response will be 200 OK.

All the following APIs will restrict the users based on the email domain and the corresponding auth method
1. Signin - Password
2. Signup - Password
3. Connect Account - MagicLink
4. Forgot Password - Password
5. Send Verification Email - MagicLink
6. SSO Signin - OpenIdConnect
7. Terminate Auth Select - Selected auth method

If the auth method list for email domain is empty of consists of the above auth method, the request will be continued, or else the api will be stopped.

Patch:
diff --git a/crates/api_models/src/user.rs b/crates/api_models/src/user.rs
index 7b5911cf1a8..ea979bfe735 100644
--- a/crates/api_models/src/user.rs
+++ b/crates/api_models/src/user.rs
@@ -305,18 +305,26 @@ pub struct CreateUserAuthenticationMethodRequest {
     pub owner_type: common_enums::Owner,
     pub auth_method: AuthConfig,
     pub allow_signup: bool,
+    pub email_domain: Option<String>,
 }
 
 #[derive(Debug, serde::Deserialize, serde::Serialize)]
-pub struct UpdateUserAuthenticationMethodRequest {
-    pub id: String,
-    // TODO: When adding more fields make config and new fields option
-    pub auth_method: AuthConfig,
+#[serde(rename_all = "snake_case")]
+pub enum UpdateUserAuthenticationMethodRequest {
+    AuthMethod {
+        id: String,
+        auth_config: AuthConfig,
+    },
+    EmailDomain {
+        owner_id: String,
+        email_domain: String,
+    },
 }
 
 #[derive(Debug, serde::Deserialize, serde::Serialize)]
 pub struct GetUserAuthenticationMethodsRequest {
-    pub auth_id: String,
+    pub auth_id: Option<String>,
+    pub email_domain: Option<String>,
 }
 
 #[derive(Debug, serde::Deserialize, serde::Serialize)]
diff --git a/crates/diesel_models/src/query/user_authentication_method.rs b/crates/diesel_models/src/query/user_authentication_method.rs
index 14a28269cec..b9ed95e37c0 100644
--- a/crates/diesel_models/src/query/user_authentication_method.rs
+++ b/crates/diesel_models/src/query/user_authentication_method.rs
@@ -64,4 +64,18 @@ impl UserAuthenticationMethod {
         )
         .await
     }
+
+    pub async fn list_user_authentication_methods_for_email_domain(
+        conn: &PgPooledConn,
+        email_domain: &str,
+    ) -> StorageResult<Vec<Self>> {
+        generics::generic_filter::<<Self as HasTable>::Table, _, _, _>(
+            conn,
+            dsl::email_domain.eq(email_domain.to_owned()),
+            None,
+            None,
+            Some(dsl::last_modified_at.asc()),
+        )
+        .await
+    }
 }
diff --git a/crates/diesel_models/src/schema.rs b/crates/diesel_models/src/schema.rs
index 178f5600542..01e21d7dd39 100644
--- a/crates/diesel_models/src/schema.rs
+++ b/crates/diesel_models/src/schema.rs
@@ -1371,6 +1371,8 @@ diesel::table! {
         allow_signup -> Bool,
         created_at -> Timestamp,
         last_modified_at -> Timestamp,
+        #[max_length = 64]
+        email_domain -> Varchar,
     }
 }
 
diff --git a/crates/diesel_models/src/schema_v2.rs b/crates/diesel_models/src/schema_v2.rs
index da2298d934b..da38c38ee2c 100644
--- a/crates/diesel_models/src/schema_v2.rs
+++ b/crates/diesel_models/src/schema_v2.rs
@@ -1318,6 +1318,8 @@ diesel::table! {
         allow_signup -> Bool,
         created_at -> Timestamp,
         last_modified_at -> Timestamp,
+        #[max_length = 64]
+        email_domain -> Varchar,
     }
 }
 
diff --git a/crates/diesel_models/src/user_authentication_method.rs b/crates/diesel_models/src/user_authentication_method.rs
index 76e1abe7575..7f3799aa7bf 100644
--- a/crates/diesel_models/src/user_authentication_method.rs
+++ b/crates/diesel_models/src/user_authentication_method.rs
@@ -17,6 +17,7 @@ pub struct UserAuthenticationMethod {
     pub allow_signup: bool,
     pub created_at: PrimitiveDateTime,
     pub last_modified_at: PrimitiveDateTime,
+    pub email_domain: String,
 }
 
 #[derive(router_derive::Setter, Clone, Debug, Insertable, router_derive::DebugAsDisplay)]
@@ -32,6 +33,7 @@ pub struct UserAuthenticationMethodNew {
     pub allow_signup: bool,
     pub created_at: PrimitiveDateTime,
     pub last_modified_at: PrimitiveDateTime,
+    pub email_domain: String,
 }
 
 #[derive(Clone, Debug, AsChangeset, router_derive::DebugAsDisplay)]
@@ -40,6 +42,7 @@ pub struct OrgAuthenticationMethodUpdateInternal {
     pub private_config: Option<Encryption>,
     pub public_config: Option<serde_json::Value>,
     pub last_modified_at: PrimitiveDateTime,
+    pub email_domain: Option<String>,
 }
 
 pub enum UserAuthenticationMethodUpdate {
@@ -47,6 +50,9 @@ pub enum UserAuthenticationMethodUpdate {
         private_config: Option<Encryption>,
         public_config: Option<serde_json::Value>,
     },
+    EmailDomain {
+        email_domain: String,
+    },
 }
 
 impl From<UserAuthenticationMethodUpdate> for OrgAuthenticationMethodUpdateInternal {
@@ -60,6 +66,13 @@ impl From<UserAuthenticationMethodUpdate> for OrgAuthenticationMethodUpdateInter
                 private_config,
                 public_config,
                 last_modified_at,
+                email_domain: None,
+            },
+            UserAuthenticationMethodUpdate::EmailDomain { email_domain } => Self {
+                private_config: None,
+                public_config: None,
+                last_modified_at,
+                email_domain: Some(email_domain),
             },
         }
     }
diff --git a/crates/router/src/core/errors/user.rs b/crates/router/src/core/errors/user.rs
index fa5f185ab82..6af269d916b 100644
--- a/crates/router/src/core/errors/user.rs
+++ b/crates/router/src/core/errors/user.rs
@@ -108,6 +108,8 @@ pub enum UserErrors {
     InvalidThemeLineage(String),
     #[error("Missing required field: email_config")]
     MissingEmailConfig,
+    #[error("Invalid Auth Method Operation: {0}")]
+    InvalidAuthMethodOperationWithMessage(String),
 }
 
 impl common_utils::errors::ErrorSwitch<api_models::errors::types::ApiErrorResponse> for UserErrors {
@@ -280,6 +282,9 @@ impl common_utils::errors::ErrorSwitch<api_models::errors::types::ApiErrorRespon
             Self::MissingEmailConfig => {
                 AER::BadRequest(ApiError::new(sub_code, 56, self.get_error_message(), None))
             }
+            Self::InvalidAuthMethodOperationWithMessage(_) => {
+                AER::BadRequest(ApiError::new(sub_code, 57, self.get_error_message(), None))
+            }
         }
     }
 }
@@ -347,6 +352,9 @@ impl UserErrors {
                 format!("Invalid field: {} in lineage", field_name)
             }
             Self::MissingEmailConfig => "Missing required field: email_config".to_string(),
+            Self::InvalidAuthMethodOperationWithMessage(operation) => {
+                format!("Invalid Auth Method Operation: {}", operation)
+            }
         }
     }
 }
diff --git a/crates/router/src/core/user.rs b/crates/router/src/core/user.rs
index 642473bdf8e..b1d99e9e1d6 100644
--- a/crates/router/src/core/user.rs
+++ b/crates/router/src/core/user.rs
@@ -7,7 +7,7 @@ use api_models::{
     payments::RedirectionResponse,
     user::{self as user_api, InviteMultipleUserResponse, NameIdUnit},
 };
-use common_enums::EntityType;
+use common_enums::{EntityType, UserAuthType};
 use common_utils::{type_name, types::keymanager::Identifier};
 #[cfg(feature = "email")]
 use diesel_models::user_role::UserRoleUpdate;
@@ -22,6 +22,7 @@ use masking::{ExposeInterface, PeekInterface, Secret};
 #[cfg(feature = "email")]
 use router_env::env;
 use router_env::logger;
+use storage_impl::errors::StorageError;
 #[cfg(not(feature = "email"))]
 use user_api::dashboard_metadata::SetMetaDataRequest;
 
@@ -151,6 +152,14 @@ pub async fn signup_token_only_flow(
     state: SessionState,
     request: user_api::SignUpRequest,
 ) -> UserResponse<user_api::TokenResponse> {
+    let user_email = domain::UserEmail::from_pii_email(request.email.clone())?;
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &user_email,
+        UserAuthType::Password,
+    )
+    .await?;
+
     let new_user = domain::NewUser::try_from(request)?;
     new_user
         .get_new_merchant()
@@ -186,9 +195,18 @@ pub async fn signin_token_only_flow(
     state: SessionState,
     request: user_api::SignInRequest,
 ) -> UserResponse<user_api::TokenResponse> {
+    let user_email = domain::UserEmail::from_pii_email(request.email)?;
+
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &user_email,
+        UserAuthType::Password,
+    )
+    .await?;
+
     let user_from_db: domain::UserFromStorage = state
         .global_store
-        .find_user_by_email(&domain::UserEmail::from_pii_email(request.email)?)
+        .find_user_by_email(&user_email)
         .await
         .to_not_found_response(UserErrors::InvalidCredentials)?
         .into();
@@ -214,10 +232,16 @@ pub async fn connect_account(
     auth_id: Option<String>,
     theme_id: Option<String>,
 ) -> UserResponse<user_api::ConnectAccountResponse> {
-    let find_user = state
-        .global_store
-        .find_user_by_email(&domain::UserEmail::from_pii_email(request.email.clone())?)
-        .await;
+    let user_email = domain::UserEmail::from_pii_email(request.email.clone())?;
+
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &user_email,
+        UserAuthType::MagicLink,
+    )
+    .await?;
+
+    let find_user = state.global_store.find_user_by_email(&user_email).await;
 
     if let Ok(found_user) = find_user {
         let user_from_db: domain::UserFromStorage = found_user.into();
@@ -408,6 +432,13 @@ pub async fn forgot_password(
 ) -> UserResponse<()> {
     let user_email = domain::UserEmail::from_pii_email(request.email)?;
 
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &user_email,
+        UserAuthType::Password,
+    )
+    .await?;
+
     let user_from_db = state
         .global_store
         .find_user_by_email(&user_email)
@@ -1749,7 +1780,15 @@ pub async fn send_verification_mail(
     auth_id: Option<String>,
     theme_id: Option<String>,
 ) -> UserResponse<()> {
-    let user_email = domain::UserEmail::try_from(req.email)?;
+    let user_email = domain::UserEmail::from_pii_email(req.email)?;
+
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &user_email,
+        UserAuthType::MagicLink,
+    )
+    .await?;
+
     let user = state
         .global_store
         .find_user_by_email(&user_email)
@@ -2308,10 +2347,30 @@ pub async fn create_user_authentication_method(
         .change_context(UserErrors::InternalServerError)
         .attach_printable("Failed to get list of auth methods for the owner id")?;
 
-    let auth_id = auth_methods
-        .first()
-        .map(|auth_method| auth_method.auth_id.clone())
-        .unwrap_or(uuid::Uuid::new_v4().to_string());
+    let (auth_id, email_domain) = if let Some(auth_method) = auth_methods.first() {
+        let email_domain = match req.email_domain {
+            Some(email_domain) => {
+                if email_domain != auth_method.email_domain {
+                    return Err(report!(UserErrors::InvalidAuthMethodOperationWithMessage(
+                        "Email domain mismatch".to_string()
+                    )));
+                }
+
+                email_domain
+            }
+            None => auth_method.email_domain.clone(),
+        };
+
+        (auth_method.auth_id.clone(), email_domain)
+    } else {
+        let email_domain =
+            req.email_domain
+                .ok_or(UserErrors::InvalidAuthMethodOperationWithMessage(
+                    "Email domain not found".to_string(),
+                ))?;
+
+        (uuid::Uuid::new_v4().to_string(), email_domain)
+    };
 
     for db_auth_method in auth_methods {
         let is_type_same = db_auth_method.auth_type == (&req.auth_method).foreign_into();
@@ -2351,6 +2410,7 @@ pub async fn create_user_authentication_method(
             allow_signup: req.allow_signup,
             created_at: now,
             last_modified_at: now,
+            email_domain,
         })
         .await
         .to_duplicate_response(UserErrors::UserAuthMethodAlreadyExists)?;
@@ -2374,25 +2434,71 @@ pub async fn update_user_authentication_method(
     .change_context(UserErrors::InternalServerError)
     .attach_printable("Failed to decode DEK")?;
 
-    let (private_config, public_config) = utils::user::construct_public_and_private_db_configs(
-        &state,
-        &req.auth_method,
-        &user_auth_encryption_key,
-        req.id.clone(),
-    )
-    .await?;
+    match req {
+        user_api::UpdateUserAuthenticationMethodRequest::AuthMethod {
+            id,
+            auth_config: auth_method,
+        } => {
+            let (private_config, public_config) =
+                utils::user::construct_public_and_private_db_configs(
+                    &state,
+                    &auth_method,
+                    &user_auth_encryption_key,
+                    id.clone(),
+                )
+                .await?;
+
+            state
+                .store
+                .update_user_authentication_method(
+                    &id,
+                    UserAuthenticationMethodUpdate::UpdateConfig {
+                        private_config,
+                        public_config,
+                    },
+                )
+                .await
+                .map_err(|error| {
+                    let user_error = match error.current_context() {
+                        StorageError::ValueNotFound(_) => {
+                            UserErrors::InvalidAuthMethodOperationWithMessage(
+                                "Auth method not found".to_string(),
+                            )
+                        }
+                        StorageError::DuplicateValue { .. } => {
+                            UserErrors::UserAuthMethodAlreadyExists
+                        }
+                        _ => UserErrors::InternalServerError,
+                    };
+                    error.change_context(user_error)
+                })?;
+        }
+        user_api::UpdateUserAuthenticationMethodRequest::EmailDomain {
+            owner_id,
+            email_domain,
+        } => {
+            let auth_methods = state
+                .store
+                .list_user_authentication_methods_for_owner_id(&owner_id)
+                .await
+                .change_context(UserErrors::InternalServerError)?;
+
+            futures::future::try_join_all(auth_methods.iter().map(|auth_method| async {
+                state
+                    .store
+                    .update_user_authentication_method(
+                        &auth_method.id,
+                        UserAuthenticationMethodUpdate::EmailDomain {
+                            email_domain: email_domain.clone(),
+                        },
+                    )
+                    .await
+                    .to_duplicate_response(UserErrors::UserAuthMethodAlreadyExists)
+            }))
+            .await?;
+        }
+    }
 
-    state
-        .store
-        .update_user_authentication_method(
-            &req.id,
-            UserAuthenticationMethodUpdate::UpdateConfig {
-                private_config,
-                public_config,
-            },
-        )
-        .await
-        .change_context(UserErrors::InvalidUserAuthMethodOperation)?;
     Ok(ApplicationResponse::StatusOk)
 }
 
@@ -2400,18 +2506,28 @@ pub async fn list_user_authentication_methods(
     state: SessionState,
     req: user_api::GetUserAuthenticationMethodsRequest,
 ) -> UserResponse<Vec<user_api::UserAuthenticationMethodResponse>> {
-    let user_authentication_methods = state
-        .store
-        .list_user_authentication_methods_for_auth_id(&req.auth_id)
-        .await
-        .change_context(UserErrors::InternalServerError)?;
+    let user_authentication_methods = match (req.auth_id, req.email_domain) {
+        (Some(auth_id), None) => state
+            .store
+            .list_user_authentication_methods_for_auth_id(&auth_id)
+            .await
+            .change_context(UserErrors::InternalServerError)?,
+        (None, Some(email_domain)) => state
+            .store
+            .list_user_authentication_methods_for_email_domain(&email_domain)
+            .await
+            .change_context(UserErrors::InternalServerError)?,
+        (Some(_), Some(_)) | (None, None) => {
+            return Err(UserErrors::InvalidUserAuthMethodOperation.into());
+        }
+    };
 
     Ok(ApplicationResponse::Json(
         user_authentication_methods
             .into_iter()
             .map(|auth_method| {
                 let auth_name = match (auth_method.auth_type, auth_method.public_config) {
-                    (common_enums::UserAuthType::OpenIdConnect, config) => {
+                    (UserAuthType::OpenIdConnect, config) => {
                         let open_id_public_config: Option<user_api::OpenIdConnectPublicConfig> =
                             config
                                 .map(|config| {
@@ -2537,6 +2653,13 @@ pub async fn sso_sign(
     )
     .await?;
 
+    utils::user::validate_email_domain_auth_type_using_db(
+        &state,
+        &email,
+        UserAuthType::OpenIdConnect,
+    )
+    .await?;
+
     // TODO: Use config to handle not found error
     let user_from_db: domain::UserFromStorage = state
         .global_store
@@ -2585,14 +2708,20 @@ pub async fn terminate_auth_select(
         .change_context(UserErrors::InternalServerError)?
         .into();
 
-    let user_authentication_method = if let Some(id) = &req.id {
-        state
-            .store
-            .get_user_authentication_method_by_id(id)
-            .await
-            .to_not_found_response(UserErrors::InvalidUserAuthMethodOperation)?
-    } else {
-        DEFAULT_USER_AUTH_METHOD.clone()
+    let user_email = domain::UserEmail::from_pii_email(user_from_db.get_email())?;
+    let auth_methods = state
+        .store
+        .list_user_authentication_methods_for_email_domain(user_email.extract_domain()?)
+        .await
+        .change_context(UserErrors::InternalServerError)?;
+
+    let user_authentication_method = match (req.id, auth_methods.is_empty()) {
+        (Some(id), _) => auth_methods
+            .into_iter()
+            .find(|auth_method| auth_method.id == id)
+            .ok_or(UserErrors::InvalidUserAuthMethodOperation)?,
+        (None, true) => DEFAULT_USER_AUTH_METHOD.clone(),
+        (None, false) => return Err(UserErrors::InvalidUserAuthMethodOperation.into()),
     };
 
     let current_flow = domain::CurrentFlow::new(user_token, domain::SPTFlow::AuthSelect.into())?;
diff --git a/crates/router/src/db/kafka_store.rs b/crates/router/src/db/kafka_store.rs
index a7e71284aaf..1eba9dd0e3d 100644
--- a/crates/router/src/db/kafka_store.rs
+++ b/crates/router/src/db/kafka_store.rs
@@ -3737,6 +3737,18 @@ impl UserAuthenticationMethodInterface for KafkaStore {
             .update_user_authentication_method(id, user_authentication_method_update)
             .await
     }
+
+    async fn list_user_authentication_methods_for_email_domain(
+        &self,
+        email_domain: &str,
+    ) -> CustomResult<
+        Vec<diesel_models::user_authentication_method::UserAuthenticationMethod>,
+        errors::StorageError,
+    > {
+        self.diesel_store
+            .list_user_authentication_methods_for_email_domain(email_domain)
+            .await
+    }
 }
 
 #[async_trait::async_trait]
diff --git a/crates/router/src/db/user_authentication_method.rs b/crates/router/src/db/user_authentication_method.rs
index a02e7bdb11f..cd918fe2060 100644
--- a/crates/router/src/db/user_authentication_method.rs
+++ b/crates/router/src/db/user_authentication_method.rs
@@ -36,6 +36,11 @@ pub trait UserAuthenticationMethodInterface {
         id: &str,
         user_authentication_method_update: storage::UserAuthenticationMethodUpdate,
     ) -> CustomResult<storage::UserAuthenticationMethod, errors::StorageError>;
+
+    async fn list_user_authentication_methods_for_email_domain(
+        &self,
+        email_domain: &str,
+    ) -> CustomResult<Vec<storage::UserAuthenticationMethod>, errors::StorageError>;
 }
 
 #[async_trait::async_trait]
@@ -57,7 +62,7 @@ impl UserAuthenticationMethodInterface for Store {
         &self,
         id: &str,
     ) -> CustomResult<storage::UserAuthenticationMethod, errors::StorageError> {
-        let conn = connection::pg_connection_write(self).await?;
+        let conn = connection::pg_connection_read(self).await?;
         storage::UserAuthenticationMethod::get_user_authentication_method_by_id(&conn, id)
             .await
             .map_err(|error| report!(errors::StorageError::from(error)))
@@ -68,7 +73,7 @@ impl UserAuthenticationMethodInterface for Store {
         &self,
         auth_id: &str,
     ) -> CustomResult<Vec<storage::UserAuthenticationMethod>, errors::StorageError> {
-        let conn = connection::pg_connection_write(self).await?;
+        let conn = connection::pg_connection_read(self).await?;
         storage::UserAuthenticationMethod::list_user_authentication_methods_for_auth_id(
             &conn, auth_id,
         )
@@ -81,7 +86,7 @@ impl UserAuthenticationMethodInterface for Store {
         &self,
         owner_id: &str,
     ) -> CustomResult<Vec<storage::UserAuthenticationMethod>, errors::StorageError> {
-        let conn = connection::pg_connection_write(self).await?;
+        let conn = connection::pg_connection_read(self).await?;
         storage::UserAuthenticationMethod::list_user_authentication_methods_for_owner_id(
             &conn, owner_id,
         )
@@ -104,6 +109,20 @@ impl UserAuthenticationMethodInterface for Store {
         .await
         .map_err(|error| report!(errors::StorageError::from(error)))
     }
+
+    #[instrument(skip_all)]
+    async fn list_user_authentication_methods_for_email_domain(
+        &self,
+        email_domain: &str,
+    ) -> CustomResult<Vec<storage::UserAuthenticationMethod>, errors::StorageError> {
+        let conn = connection::pg_connection_read(self).await?;
+        storage::UserAuthenticationMethod::list_user_authentication_methods_for_email_domain(
+            &conn,
+            email_domain,
+        )
+        .await
+        .map_err(|error| report!(errors::StorageError::from(error)))
+    }
 }
 
 #[async_trait::async_trait]
@@ -130,6 +149,7 @@ impl UserAuthenticationMethodInterface for MockDb {
             allow_signup: user_authentication_method.allow_signup,
             created_at: user_authentication_method.created_at,
             last_modified_at: user_authentication_method.last_modified_at,
+            email_domain: user_authentication_method.email_domain,
         };
 
         user_authentication_methods.push(user_authentication_method.clone());
@@ -222,6 +242,13 @@ impl UserAuthenticationMethodInterface for MockDb {
                         last_modified_at: common_utils::date_time::now(),
                         ..auth_method_inner.to_owned()
                     },
+                    storage::UserAuthenticationMethodUpdate::EmailDomain { email_domain } => {
+                        storage::UserAuthenticationMethod {
+                            email_domain: email_domain.to_owned(),
+                            last_modified_at: common_utils::date_time::now(),
+                            ..auth_method_inner.to_owned()
+                        }
+                    }
                 };
                 auth_method_inner.to_owned()
             })
@@ -232,4 +259,20 @@ impl UserAuthenticationMethodInterface for MockDb {
                 .into(),
             )
     }
+
+    #[instrument(skip_all)]
+    async fn list_user_authentication_methods_for_email_domain(
+        &self,
+        email_domain: &str,
+    ) -> CustomResult<Vec<storage::UserAuthenticationMethod>, errors::StorageError> {
+        let user_authentication_methods = self.user_authentication_methods.lock().await;
+
+        let user_authentication_methods_list: Vec<_> = user_authentication_methods
+            .iter()
+            .filter(|auth_method_inner| auth_method_inner.email_domain == email_domain)
+            .cloned()
+            .collect();
+
+        Ok(user_authentication_methods_list)
+    }
 }
diff --git a/crates/router/src/types/domain/user.rs b/crates/router/src/types/domain/user.rs
index 6efaac7bfed..569e7f9a99f 100644
--- a/crates/router/src/types/domain/user.rs
+++ b/crates/router/src/types/domain/user.rs
@@ -138,6 +138,15 @@ impl UserEmail {
     pub fn get_secret(self) -> Secret<String, pii::EmailStrategy> {
         (*self.0).clone()
     }
+
+    pub fn extract_domain(&self) -> UserResult<&str> {
+        let (_username, domain) = self
+            .peek()
+            .split_once('@')
+            .ok_or(UserErrors::InternalServerError)?;
+
+        Ok(domain)
+    }
 }
 
 impl TryFrom<pii::Email> for UserEmail {
diff --git a/crates/router/src/types/domain/user/user_authentication_method.rs b/crates/router/src/types/domain/user/user_authentication_method.rs
index 570e144961a..29c588f15e1 100644
--- a/crates/router/src/types/domain/user/user_authentication_method.rs
+++ b/crates/router/src/types/domain/user/user_authentication_method.rs
@@ -14,4 +14,5 @@ pub static DEFAULT_USER_AUTH_METHOD: Lazy<UserAuthenticationMethod> =
         allow_signup: true,
         created_at: common_utils::date_time::now(),
         last_modified_at: common_utils::date_time::now(),
+        email_domain: String::from("hyperswitch"),
     });
diff --git a/crates/router/src/utils/user.rs b/crates/router/src/utils/user.rs
index abd59684243..b8ffcf836d7 100644
--- a/crates/router/src/utils/user.rs
+++ b/crates/router/src/utils/user.rs
@@ -5,7 +5,7 @@ use common_enums::UserAuthType;
 use common_utils::{
     encryption::Encryption, errors::CustomResult, id_type, type_name, types::keymanager::Identifier,
 };
-use diesel_models::{organization, organization::OrganizationBridge};
+use diesel_models::organization::{self, OrganizationBridge};
 use error_stack::ResultExt;
 use masking::{ExposeInterface, Secret};
 use redis_interface::RedisConnectionPool;
@@ -312,3 +312,23 @@ pub fn create_merchant_account_request_for_org(
         pm_collect_link_config: None,
     })
 }
+
+pub async fn validate_email_domain_auth_type_using_db(
+    state: &SessionState,
+    email: &domain::UserEmail,
+    required_auth_type: UserAuthType,
+) -> UserResult<()> {
+    let domain = email.extract_domain()?;
+    let user_auth_methods = state
+        .store
+        .list_user_authentication_methods_for_email_domain(domain)
+        .await
+        .change_context(UserErrors::InternalServerError)?;
+
+    (user_auth_methods.is_empty()
+        || user_auth_methods
+            .iter()
+            .any(|auth_method| auth_method.auth_type == required_auth_type))
+    .then_some(())
+    .ok_or(UserErrors::InvalidUserAuthMethodOperation.into())
+}
diff --git a/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/down.sql b/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/down.sql
new file mode 100644
index 00000000000..9f3560069c7
--- /dev/null
+++ b/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/down.sql
@@ -0,0 +1,3 @@
+-- This file should undo anything in `up.sql`
+DROP INDEX email_domain_index;
+ALTER TABLE user_authentication_methods DROP COLUMN email_domain;
diff --git a/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/up.sql b/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/up.sql
new file mode 100644
index 00000000000..831f10162ca
--- /dev/null
+++ b/migrations/2024-12-11-092624_add-email-domain-in-auth-methods/up.sql
@@ -0,0 +1,6 @@
+-- Your SQL goes here
+ALTER TABLE user_authentication_methods ADD COLUMN email_domain VARCHAR(64);
+UPDATE user_authentication_methods SET email_domain = auth_id WHERE email_domain IS NULL;
+ALTER TABLE user_authentication_methods ALTER COLUMN email_domain SET NOT NULL;
+
+CREATE INDEX email_domain_index ON user_authentication_methods (email_domain);