diff --git a/mal.d b/mal.d
index 0f74cf8..43cbe68 100644
--- a/mal.d
+++ b/mal.d
@@ -71,10 +71,9 @@ main(string[] args)
 
 	fqdn = hostName() ~ ".local";
 	mailHeaders = toAddrs = [];
-	subject = "";
 	useSmtps = true;
 	authUser = message = messageFile = passPhrase =
-		realName = serverAddr = serverPort = null;
+		realName = serverAddr = serverPort = subject = null;
 
 	try {
 		import std.getopt : config;
@@ -162,6 +161,10 @@ main(string[] args)
 		warn("warning: -P not supplied, using empty passphrase");
 		passPhrase = "";
 	}
+	if (!subject) {
+		warn("warning: -S not supplied, using empty subject line");
+		subject = "";
+	}
 
 	try {
 		messageBuf =