diff --git a/lib/config/constants.ts b/lib/config/constants.ts
new file mode 100644
index 0000000..963a7fa
--- /dev/null
+++ b/lib/config/constants.ts
@@ -0,0 +1,55 @@
+import { Config, Value, Variants } from "./builder"
+
+export const smtpConfig = Value.union(
+  {
+    name: "SMTP",
+    description: "Optionally provide an SMTP server for sending email",
+    required: { default: "disabled" },
+  },
+  Variants.of({
+    disabled: { name: "Disabled", spec: Config.of({}) },
+    system: { name: "System Credentials", spec: Config.of({}) },
+    custom: {
+      name: "Custom Credentials",
+      spec: Config.of({
+        server: Value.text({
+          name: "SMTP Server",
+          required: {
+            default: null,
+          },
+        }),
+        port: Value.number({
+          name: "Port",
+          required: { default: 587 },
+          min: 1,
+          max: 65535,
+          integer: true,
+        }),
+        from: Value.text({
+          name: "From Address",
+          required: {
+            default: null,
+          },
+          placeholder: "<name>test@example.com",
+          inputmode: "email",
+        }),
+        login: Value.text({
+          name: "Login",
+          required: {
+            default: null,
+          },
+        }),
+        password: Value.text({
+          name: "Password",
+          required: false,
+        }),
+        tls: Value.toggle({
+          name: "Require Transport Security",
+          default: true,
+          description:
+            "Require TLS transport security. If disabled, email will use plaintext by default and TLS via STARTTLS <strong>if the SMTP server supports it</strong>. If enabled, email will refuse to connect unless the server supports STARTTLS.",
+        }),
+      }),
+    },
+  }),
+)