message with missing to value

test/message02.sip

@@ -0,0 +1,11 @@
+MESSAGE sip:[email protected] SIP/2.0
+Via: SIP/2.0/UDP fox.iptel.org:5060
+From: "bogdan" <sip:[email protected]>;tag=0e99b1e7-ff50-4875-94ef-4ca5c27e2705
+To: 
+Call-ID: [email protected]
+CSeq: 7 MESSAGE
+Contact: <sip:195.37.78.169:11457>
+User-Agent: Windows RTC/1.0
+Content-Type: text/plain
+Content-Length: 4
+