diff --git a/scripts/odysseus-mail b/scripts/odysseus-mail
index 06bf8d9cc..fcd8c6a5a 100755
--- a/scripts/odysseus-mail
+++ b/scripts/odysseus-mail
@@ -108,6 +108,8 @@ def _q(name: str) -> str:
 
 
 def _split_recipients(value: str) -> list[str]:
+    if not isinstance(value, str):
+        return []
     return [r.strip() for r in (value or "").split(",") if r.strip()]
 
 
diff --git a/tests/cli/test_mail_cli_recipients.py b/tests/cli/test_mail_cli_recipients.py
index e21d70e6a..0e5e9fe7c 100644
--- a/tests/cli/test_mail_cli_recipients.py
+++ b/tests/cli/test_mail_cli_recipients.py
@@ -48,3 +48,10 @@ def test_recipient_list_rejects_empty_envelope(monkeypatch):
         assert exc.code == 1
     else:
         raise AssertionError("expected empty recipient list to exit")
+
+
+def test_split_recipients_ignores_non_string_values(monkeypatch):
+    cli = _load_mail_cli(monkeypatch)
+
+    assert cli._split_recipients(None) == []
+    assert cli._split_recipients(["a@example.test"]) == []