diff --git a/wallace/modules.py b/wallace/modules.py
--- a/wallace/modules.py
+++ b/wallace/modules.py
@@ -153,6 +153,10 @@
     if conf.debuglevel > 8:
         smtp.set_debuglevel(1)
 
+    # Sender can't be a list
+    if isinstance(sender, list):
+        sender = sender[0]
+
     success = False
     attempt = 1