diff --git a/docs/API/admin_api.md b/docs/API/admin_api.md
index 58d702347..57fb6bc6a 100644
--- a/docs/API/admin_api.md
+++ b/docs/API/admin_api.md
@@ -392,6 +392,19 @@ Note: Available `:permission_group` is currently moderator and admin. 404 is ret
   - `email`
   - `name`, optional
 
+- Response:
+  - On success: `204`, empty response
+  - On failure:
+    - 400 Bad Request, JSON:
+
+    ```json
+      [
+        {
+          "error": "Appropriate error message here"
+        }
+      ]
+    ```
+
 ## `GET /api/pleroma/admin/users/:nickname/password_reset`
 
 ### Get a password reset token for a given nickname
diff --git a/lib/pleroma/web/admin_api/admin_api_controller.ex b/lib/pleroma/web/admin_api/admin_api_controller.ex
index ca5439920..fdbd24acb 100644
--- a/lib/pleroma/web/admin_api/admin_api_controller.ex
+++ b/lib/pleroma/web/admin_api/admin_api_controller.ex
@@ -576,9 +576,8 @@ def relay_unfollow(%{assigns: %{user: admin}} = conn, %{"relay_url" => target})
 
   @doc "Sends registration invite via email"
   def email_invite(%{assigns: %{user: user}} = conn, %{"email" => email} = params) do
-    with true <-
-           Config.get([:instance, :invites_enabled]) &&
-             !Config.get([:instance, :registrations_open]),
+    with {_, false} <- {:registrations_open, Config.get([:instance, :registrations_open])},
+         {_, true} <- {:invites_enabled, Config.get([:instance, :invites_enabled])},
          {:ok, invite_token} <- UserInviteToken.create_invite(),
          email <-
            Pleroma.Emails.UserEmail.user_invitation_email(
@@ -589,6 +588,18 @@ def email_invite(%{assigns: %{user: user}} = conn, %{"email" => email} = params)
            ),
          {:ok, _} <- Pleroma.Emails.Mailer.deliver(email) do
       json_response(conn, :no_content, "")
+    else
+      {:registrations_open, _} ->
+        errors(
+          conn,
+          {:error, "To send invites you need to set the `registrations_open` option to false."}
+        )
+
+      {:invites_enabled, _} ->
+        errors(
+          conn,
+          {:error, "To send invites you need to set the `invites_enabled` option to true."}
+        )
     end
   end
 
diff --git a/test/web/admin_api/admin_api_controller_test.exs b/test/web/admin_api/admin_api_controller_test.exs
index fe8a086d8..f02f6ae7a 100644
--- a/test/web/admin_api/admin_api_controller_test.exs
+++ b/test/web/admin_api/admin_api_controller_test.exs
@@ -625,6 +625,39 @@ test "it returns 403 if requested by a non-admin" do
 
       assert json_response(conn, :forbidden)
     end
+
+    test "email with +", %{conn: conn, admin: admin} do
+      recipient_email = "foo+bar@baz.com"
+
+      conn
+      |> put_req_header("content-type", "application/json;charset=utf-8")
+      |> post("/api/pleroma/admin/users/email_invite", %{email: recipient_email})
+      |> json_response(:no_content)
+
+      token_record =
+        Pleroma.UserInviteToken
+        |> Repo.all()
+        |> List.last()
+
+      assert token_record
+      refute token_record.used
+
+      notify_email = Config.get([:instance, :notify_email])
+      instance_name = Config.get([:instance, :name])
+
+      email =
+        Pleroma.Emails.UserEmail.user_invitation_email(
+          admin,
+          token_record,
+          recipient_email
+        )
+
+      Swoosh.TestAssertions.assert_email_sent(
+        from: {instance_name, notify_email},
+        to: recipient_email,
+        html_body: email.html_body
+      )
+    end
   end
 
   describe "POST /api/pleroma/admin/users/email_invite, with invalid config" do
@@ -637,7 +670,8 @@ test "it returns 500 if `invites_enabled` is not enabled", %{conn: conn} do
 
       conn = post(conn, "/api/pleroma/admin/users/email_invite?email=foo@bar.com&name=JD")
 
-      assert json_response(conn, :internal_server_error)
+      assert json_response(conn, :bad_request) ==
+               "To send invites you need to set the `invites_enabled` option to true."
     end
 
     test "it returns 500 if `registrations_open` is enabled", %{conn: conn} do
@@ -646,7 +680,8 @@ test "it returns 500 if `registrations_open` is enabled", %{conn: conn} do
 
       conn = post(conn, "/api/pleroma/admin/users/email_invite?email=foo@bar.com&name=JD")
 
-      assert json_response(conn, :internal_server_error)
+      assert json_response(conn, :bad_request) ==
+               "To send invites you need to set the `registrations_open` option to false."
     end
   end