diff --git a/tests/test_utils_sendmail.py b/tests/test_utils_sendmail.py
index f80dd53db..28bf6a97e 100644
--- a/tests/test_utils_sendmail.py
+++ b/tests/test_utils_sendmail.py
@@ -14,6 +14,7 @@ def test_sendmail_mime_format_in_tmux():
     assert tmux_tty and os.path.exists(tmux_tty), f"Invalid TMUX_TTY: {tmux_tty}"
 
     # Define test message parameters
+    to_addr=f"| tee {tmux_tty}"
     from_addr = "robot@local"
     subject = "MIME Format Test"
     body = "This is the MIME body."