Fix syntax error in v-delete-letsencrypt-domain

bin/v-delete-letsencrypt-domain

@@ -82,7 +82,7 @@ fi
 $BIN/v-restart-web $restart
 check_result $? "Web restart failed" >/dev/null
 
-if [ -z "$mail"]; then
+if [ -z "$mail" ]; then
     # Restarting proxy
     if [ ! -z "$PROXY_SYSTEM" ]; then
         $BIN/v-restart-web $restart >/dev/null