diff --git a/src/MDBlockedMailserverSet.php b/src/MDBlockedMailserverSet.php
new file mode 100644
index 0000000..7ac2c54
--- /dev/null
+++ b/src/MDBlockedMailserverSet.php
@@ -0,0 +1,20 @@
+<?PHP
+/**
+ * Contains a class listing blocked mailservers. Mail servers may e.g. be blocked
+ * for not accepting mails from @museum-digital.de.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Contains a class listing blocked mailservers. Mail servers may e.g. be blocked
+ * for not accepting mails from @museum-digital.de.
+ */
+final class MDBlockedMailserverSet extends MDValueSet {
+
+    const BLOCKED_DOMAINS = [
+        "@t-online.de",
+    ];
+
+}