Don't require the `--jserver` command line flag.

Just assume the JIDs domain part to be the server.
The mattn/go-xmpp lib will find the appropriate server
to connect to by resolving the xmpp-client SRV record.

go-sendxmpp.go

@@ -260,8 +260,8 @@ func main() {
 		recipients[i] = validatedJid
 	}
 
-	// Read configuration file if user, server or password is not specified.
-	if *flagUser == "" || *flagServer == "" || *flagPassword == "" {
+	// Read configuration file if user or password is not specified.
+	if *flagUser == "" || *flagPassword == "" {
 		// Read configuration from file.
 		config, err := parseConfig(*flagFile)
 		if err != nil {
@@ -286,6 +286,11 @@ func main() {
 		server = *flagServer
 	}
 
+	// Use the JIDs server part if no server is specified.
+	if server == "" {
+		server = strings.Split(user, "@")[1]
+	}
+
 	// Overwrite password if specified via command line flag.
 	if *flagPassword != "" {
 		password = *flagPassword