diff --git a/changes/24321-exclude-custom-source-without-email b/changes/24321-exclude-custom-source-without-email
new file mode 100644
index 0000000000..f0c33e9c38
--- /dev/null
+++ b/changes/24321-exclude-custom-source-without-email
@@ -0,0 +1,2 @@
+- Exclude any custom sourced "users" from the host details "used by" display if Fleet doesn't have
+  an email for them.
diff --git a/frontend/interfaces/host.ts b/frontend/interfaces/host.ts
index 762dc5b76e..c0a9f0cab5 100644
--- a/frontend/interfaces/host.ts
+++ b/frontend/interfaces/host.ts
@@ -119,7 +119,10 @@ export const mapDeviceUsersForDisplay = (
         idpUser = d;
         break;
       case "custom":
-        customUser = d;
+        // exclude custom user without email
+        if (d.email) {
+          customUser = d;
+        }
         break;
       default:
         newDeviceMapping.push(getDeviceUserForDisplay(d));
diff --git a/frontend/pages/hosts/details/HostDetailsPage/HostDetailsPage.tsx b/frontend/pages/hosts/details/HostDetailsPage/HostDetailsPage.tsx
index 8947a18cf4..8e46f71971 100644
--- a/frontend/pages/hosts/details/HostDetailsPage/HostDetailsPage.tsx
+++ b/frontend/pages/hosts/details/HostDetailsPage/HostDetailsPage.tsx
@@ -39,7 +39,6 @@ import {
   IQueryKeyQueriesLoadAll,
   ISchedulableQuery,
 } from "interfaces/schedulable_query";
-import { IHostScript } from "interfaces/script";
 
 import {
   normalizeEmptyValues,