diff --git a/Cargo.lock b/Cargo.lock
index d2d40d5eb..a53843f6e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2817,6 +2817,7 @@ dependencies = [
  "elementtree",
  "hound",
  "lemmy_api_common",
+ "lemmy_api_crud",
  "lemmy_db_schema",
  "lemmy_db_views",
  "lemmy_db_views_actor",
diff --git a/crates/api/Cargo.toml b/crates/api/Cargo.toml
index 9506049ee..87879f6cd 100644
--- a/crates/api/Cargo.toml
+++ b/crates/api/Cargo.toml
@@ -43,3 +43,4 @@ serial_test = { workspace = true }
 tokio = { workspace = true }
 elementtree = "1.2.3"
 pretty_assertions = { workspace = true }
+lemmy_api_crud = { workspace = true }
diff --git a/crates/api/src/site/registration_applications/approve.rs b/crates/api/src/site/registration_applications/approve.rs
index 823af54c4..dcde78117 100644
--- a/crates/api/src/site/registration_applications/approve.rs
+++ b/crates/api/src/site/registration_applications/approve.rs
@@ -1,4 +1,5 @@
-use actix_web::web::{Data, Json};
+use activitypub_federation::config::Data;
+use actix_web::web::Json;
 use lemmy_api_common::{
   context::LemmyContext,
   site::{ApproveRegistrationApplication, RegistrationApplicationResponse},
@@ -10,10 +11,13 @@ use lemmy_db_schema::{
     registration_application::{RegistrationApplication, RegistrationApplicationUpdateForm},
   },
   traits::Crud,
-  utils::diesel_string_update,
+  utils::{diesel_string_update, get_conn},
 };
 use lemmy_db_views::structs::{LocalUserView, RegistrationApplicationView};
-use lemmy_utils::{error::LemmyResult, LemmyErrorType};
+use lemmy_utils::{
+  error::{LemmyError, LemmyResult},
+  LemmyErrorType,
+};
 
 pub async fn approve_registration_application(
   data: Json<ApproveRegistrationApplication>,
@@ -25,34 +29,46 @@ pub async fn approve_registration_application(
   // Only let admins do this
   is_admin(&local_user_view)?;
 
-  // Update the registration with reason, admin_id
-  let deny_reason = diesel_string_update(data.deny_reason.as_deref());
-  let app_form = RegistrationApplicationUpdateForm {
-    admin_id: Some(Some(local_user_view.person.id)),
-    deny_reason,
-  };
+  let pool = &mut context.pool();
+  let conn = &mut get_conn(pool).await?;
+  let tx_data = data.clone();
+  let approved_user_id = conn
+    .build_transaction()
+    .run(|conn| {
+      Box::pin(async move {
+        // Update the registration with reason, admin_id
+        let deny_reason = diesel_string_update(tx_data.deny_reason.as_deref());
+        let app_form = RegistrationApplicationUpdateForm {
+          admin_id: Some(Some(local_user_view.person.id)),
+          deny_reason,
+        };
 
-  let registration_application =
-    RegistrationApplication::update(&mut context.pool(), app_id, &app_form).await?;
+        let registration_application =
+          RegistrationApplication::update(&mut conn.into(), app_id, &app_form).await?;
 
-  // Update the local_user row
-  let local_user_form = LocalUserUpdateForm {
-    accepted_application: Some(data.approve),
-    ..Default::default()
-  };
+        // Update the local_user row
+        let local_user_form = LocalUserUpdateForm {
+          accepted_application: Some(tx_data.approve),
+          ..Default::default()
+        };
 
-  let approved_user_id = registration_application.local_user_id;
-  LocalUser::update(&mut context.pool(), approved_user_id, &local_user_form).await?;
+        let approved_user_id = registration_application.local_user_id;
+        LocalUser::update(&mut conn.into(), approved_user_id, &local_user_form).await?;
+
+        Ok::<_, LemmyError>(approved_user_id)
+      }) as _
+    })
+    .await?;
 
   if data.approve {
     let approved_local_user_view = LocalUserView::read(&mut context.pool(), approved_user_id)
       .await?
       .ok_or(LemmyErrorType::CouldntFindLocalUser)?;
-
     if approved_local_user_view.local_user.email.is_some() {
+      // Email sending may fail, but this won't revert the application approval
       send_application_approved_email(&approved_local_user_view, context.settings()).await?;
     }
-  }
+  };
 
   // Read the view
   let registration_application = RegistrationApplicationView::read(&mut context.pool(), app_id)
diff --git a/crates/api/src/site/registration_applications/list.rs b/crates/api/src/site/registration_applications/list.rs
index df86b11d5..877e83796 100644
--- a/crates/api/src/site/registration_applications/list.rs
+++ b/crates/api/src/site/registration_applications/list.rs
@@ -1,4 +1,5 @@
-use actix_web::web::{Data, Json, Query};
+use activitypub_federation::config::Data;
+use actix_web::web::{Json, Query};
 use lemmy_api_common::{
   context::LemmyContext,
   site::{ListRegistrationApplications, ListRegistrationApplicationsResponse},
diff --git a/crates/api/src/site/registration_applications/mod.rs b/crates/api/src/site/registration_applications/mod.rs
index e904f597d..c9a63cdef 100644
--- a/crates/api/src/site/registration_applications/mod.rs
+++ b/crates/api/src/site/registration_applications/mod.rs
@@ -1,4 +1,6 @@
 pub mod approve;
 pub mod get;
 pub mod list;
+#[cfg(test)]
+mod tests;
 pub mod unread_count;
diff --git a/crates/api/src/site/registration_applications/tests.rs b/crates/api/src/site/registration_applications/tests.rs
new file mode 100644
index 000000000..062fa550f
--- /dev/null
+++ b/crates/api/src/site/registration_applications/tests.rs
@@ -0,0 +1,428 @@
+use crate::site::registration_applications::{
+  approve::approve_registration_application,
+  list::list_registration_applications,
+  unread_count::get_unread_registration_application_count,
+};
+use activitypub_federation::config::Data;
+use actix_web::web::{Json, Query};
+use lemmy_api_common::{
+  context::LemmyContext,
+  site::{
+    ApproveRegistrationApplication,
+    EditSite,
+    GetUnreadRegistrationApplicationCountResponse,
+    ListRegistrationApplicationsResponse,
+  },
+};
+use lemmy_api_crud::site::update::update_site;
+use lemmy_db_schema::{
+  newtypes::InstanceId,
+  source::{
+    instance::Instance,
+    local_site::{LocalSite, LocalSiteInsertForm},
+    local_site_rate_limit::{LocalSiteRateLimit, LocalSiteRateLimitInsertForm},
+    local_user::{LocalUser, LocalUserInsertForm, LocalUserUpdateForm},
+    person::{Person, PersonInsertForm},
+    registration_application::{RegistrationApplication, RegistrationApplicationInsertForm},
+    site::{Site, SiteInsertForm},
+  },
+  traits::Crud,
+  utils::DbPool,
+  RegistrationMode,
+};
+use lemmy_db_views::structs::LocalUserView;
+use lemmy_utils::{error::LemmyResult, LemmyErrorType, CACHE_DURATION_API};
+use serial_test::serial;
+
+#[allow(clippy::unwrap_used)]
+async fn create_test_site(context: &Data<LemmyContext>) -> LemmyResult<(Instance, LocalUserView)> {
+  let pool = &mut context.pool();
+
+  let inserted_instance = Instance::read_or_create(pool, "my_domain.tld".to_string())
+    .await
+    .expect("Create test instance");
+
+  let admin_person = Person::create(
+    pool,
+    &PersonInsertForm::test_form(inserted_instance.id, "admin"),
+  )
+  .await?;
+  LocalUser::create(
+    pool,
+    &LocalUserInsertForm::test_form_admin(admin_person.id),
+    vec![],
+  )
+  .await?;
+
+  let admin_local_user_view = LocalUserView::read_person(pool, admin_person.id)
+    .await?
+    .unwrap();
+
+  let site_form = SiteInsertForm::builder()
+    .name("test site".to_string())
+    .instance_id(inserted_instance.id)
+    .build();
+  let site = Site::create(pool, &site_form).await.unwrap();
+
+  // Create a local site, since this is necessary for determining if email verification is
+  // required
+  let local_site_form = LocalSiteInsertForm::builder()
+    .site_id(site.id)
+    .require_email_verification(Some(true))
+    .application_question(Some(".".to_string()))
+    .registration_mode(Some(RegistrationMode::RequireApplication))
+    .site_setup(Some(true))
+    .build();
+  let local_site = LocalSite::create(pool, &local_site_form).await.unwrap();
+
+  // Required to have a working local SiteView when updating the site to change email verification
+  // requirement or registration mode
+  let rate_limit_form = LocalSiteRateLimitInsertForm::builder()
+    .local_site_id(local_site.id)
+    .build();
+  LocalSiteRateLimit::create(pool, &rate_limit_form)
+    .await
+    .unwrap();
+
+  Ok((inserted_instance, admin_local_user_view))
+}
+
+async fn signup(
+  pool: &mut DbPool<'_>,
+  instance_id: InstanceId,
+  name: &str,
+  email: Option<&str>,
+) -> LemmyResult<(LocalUser, RegistrationApplication)> {
+  let person_insert_form = PersonInsertForm::test_form(instance_id, name);
+  let person = Person::create(pool, &person_insert_form).await?;
+
+  let local_user_insert_form = match email {
+    Some(email) => LocalUserInsertForm {
+      email: Some(email.to_string()),
+      email_verified: Some(false),
+      ..LocalUserInsertForm::test_form(person.id)
+    },
+    None => LocalUserInsertForm::test_form(person.id),
+  };
+
+  let local_user = LocalUser::create(pool, &local_user_insert_form, vec![]).await?;
+
+  let application_insert_form = RegistrationApplicationInsertForm {
+    local_user_id: local_user.id,
+    answer: "x".to_string(),
+  };
+  let application = RegistrationApplication::create(pool, &application_insert_form).await?;
+
+  Ok((local_user, application))
+}
+
+#[allow(clippy::unwrap_used)]
+async fn get_application_statuses(
+  context: &Data<LemmyContext>,
+  admin: LocalUserView,
+) -> LemmyResult<(
+  Json<GetUnreadRegistrationApplicationCountResponse>,
+  Json<ListRegistrationApplicationsResponse>,
+  Json<ListRegistrationApplicationsResponse>,
+)> {
+  let application_count =
+    get_unread_registration_application_count(context.reset_request_count(), admin.clone()).await?;
+
+  let unread_applications = list_registration_applications(
+    Query::from_query("unread_only=true").unwrap(),
+    context.reset_request_count(),
+    admin.clone(),
+  )
+  .await?;
+
+  let all_applications = list_registration_applications(
+    Query::from_query("unread_only=false").unwrap(),
+    context.reset_request_count(),
+    admin,
+  )
+  .await?;
+
+  Ok((application_count, unread_applications, all_applications))
+}
+
+#[allow(clippy::indexing_slicing)]
+#[allow(clippy::unwrap_used)]
+#[tokio::test]
+#[serial]
+async fn test_application_approval() -> LemmyResult<()> {
+  let context = LemmyContext::init_test_context().await;
+  let pool = &mut context.pool();
+
+  let (instance, admin_local_user_view) = create_test_site(&context).await?;
+
+  // Non-unread counts unfortunately are duplicated due to different types (i64 vs usize)
+  let mut expected_total_applications = 0;
+  let mut expected_unread_applications = 0u8;
+
+  let (local_user_with_email, app_with_email) =
+    signup(pool, instance.id, "user_w_email", Some("lemmy@localhost")).await?;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // When email verification is required and the email is not verified the application should not
+  // be visible to admins
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  LocalUser::update(
+    pool,
+    local_user_with_email.id,
+    &LocalUserUpdateForm {
+      email_verified: Some(true),
+      ..Default::default()
+    },
+  )
+  .await?;
+
+  expected_total_applications += 1;
+  expected_unread_applications += 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // When email verification is required and the email is verified the application should be
+  // visible to admins
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert!(
+    !unread_applications.registration_applications[0]
+      .creator_local_user
+      .accepted_application
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  let approval = approve_registration_application(
+    Json(ApproveRegistrationApplication {
+      id: app_with_email.id,
+      approve: true,
+      deny_reason: None,
+    }),
+    context.reset_request_count(),
+    admin_local_user_view.clone(),
+  )
+  .await;
+  // Approval should be processed up until email sending is attempted
+  assert!(approval.is_err_and(|e| e.error_type == LemmyErrorType::NoEmailSetup));
+
+  expected_unread_applications -= 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // When the application is approved it should only be returned for unread queries
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+  assert!(
+    all_applications.registration_applications[0]
+      .creator_local_user
+      .accepted_application
+  );
+
+  let (_local_user, app_with_email_2) = signup(
+    pool,
+    instance.id,
+    "user_w_email_2",
+    Some("lemmy2@localhost"),
+  )
+  .await?;
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // Email not verified, so application still not visible
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  update_site(
+    Json(EditSite {
+      require_email_verification: Some(false),
+      ..Default::default()
+    }),
+    context.reset_request_count(),
+    admin_local_user_view.clone(),
+  )
+  .await?;
+
+  // TODO: There is probably a better way to ensure cache invalidation
+  tokio::time::sleep(CACHE_DURATION_API).await;
+
+  expected_total_applications += 1;
+  expected_unread_applications += 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // After disabling email verification the application should now be visible
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  approve_registration_application(
+    Json(ApproveRegistrationApplication {
+      id: app_with_email_2.id,
+      approve: false,
+      deny_reason: None,
+    }),
+    context.reset_request_count(),
+    admin_local_user_view.clone(),
+  )
+  .await?;
+
+  expected_unread_applications -= 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // Denied applications should not be marked as unread
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  signup(pool, instance.id, "user_wo_email", None).await?;
+
+  expected_total_applications += 1;
+  expected_unread_applications += 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // New user without email should immediately be visible
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  signup(pool, instance.id, "user_w_email_3", None).await?;
+
+  expected_total_applications += 1;
+  expected_unread_applications += 1;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // New user with email should immediately be visible
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  update_site(
+    Json(EditSite {
+      registration_mode: Some(RegistrationMode::Open),
+      ..Default::default()
+    }),
+    context.reset_request_count(),
+    admin_local_user_view.clone(),
+  )
+  .await?;
+
+  // TODO: There is probably a better way to ensure cache invalidation
+  tokio::time::sleep(CACHE_DURATION_API).await;
+
+  let (application_count, unread_applications, all_applications) =
+    get_application_statuses(&context, admin_local_user_view.clone()).await?;
+
+  // TODO: At this time applications do not get approved when switching to open registration, so the
+  //       numbers will not change. See https://github.com/LemmyNet/lemmy/issues/4969
+  // expected_application_count = 0;
+  // expected_unread_applications_len = 0;
+
+  // When applications are not required all previous applications should become approved but still
+  // visible
+  assert_eq!(
+    application_count.registration_applications,
+    i64::from(expected_unread_applications),
+  );
+  assert_eq!(
+    unread_applications.registration_applications.len(),
+    usize::from(expected_unread_applications),
+  );
+  assert_eq!(
+    all_applications.registration_applications.len(),
+    expected_total_applications,
+  );
+
+  LocalSite::delete(pool).await?;
+  // Instance deletion cascades cleanup of all created persons
+  Instance::delete(pool, instance.id).await?;
+
+  Ok(())
+}
diff --git a/crates/api/src/site/registration_applications/unread_count.rs b/crates/api/src/site/registration_applications/unread_count.rs
index a12ecb1d3..5cc391ed0 100644
--- a/crates/api/src/site/registration_applications/unread_count.rs
+++ b/crates/api/src/site/registration_applications/unread_count.rs
@@ -1,4 +1,5 @@
-use actix_web::web::{Data, Json};
+use activitypub_federation::config::Data;
+use actix_web::web::Json;
 use lemmy_api_common::{
   context::LemmyContext,
   site::GetUnreadRegistrationApplicationCountResponse,
diff --git a/crates/api_crud/src/site/create.rs b/crates/api_crud/src/site/create.rs
index 6b1909966..9dcd1595a 100644
--- a/crates/api_crud/src/site/create.rs
+++ b/crates/api_crud/src/site/create.rs
@@ -1,6 +1,6 @@
 use crate::site::{application_question_check, site_default_post_listing_type_check};
-use activitypub_federation::http_signatures::generate_actor_keypair;
-use actix_web::web::{Data, Json};
+use activitypub_federation::{config::Data, http_signatures::generate_actor_keypair};
+use actix_web::web::Json;
 use lemmy_api_common::{
   context::LemmyContext,
   site::{CreateSite, SiteResponse},