diff --git a/install_amavis.sh b/install_amavis.sh
index 1424fcd..691ddca 100755
--- a/install_amavis.sh
+++ b/install_amavis.sh
@@ -396,8 +396,13 @@ while [[ "$SASL_AUTH_ENABLED" != "yes" &&
       SASL_AUTH_ENABLED=${SASL_AUTH_ENABLED,,}
    fi
 
-   if [[ "$SASL_AUTH_ENABLED" != "yes" && "$SASL_AUTH_ENABLED" != "no" ]] ; then
-      _SASL_AUTH_ENABLED=""
+   [[ -z "${SASL_AUTH_ENABLED}" ]] && SASL_AUTH_ENABLED=${_SASL_AUTH_ENABLED}
+
+   if [[ "$SASL_AUTH_ENABLED" != "yes" &&
+         "$SASL_AUTH_ENABLED" != "true" &&
+         "$SASL_AUTH_ENABLED" != "false" &&
+         "$SASL_AUTH_ENABLED" != "no" ]] ; then
+      SASL_AUTH_ENABLED=""
       echo -e  "\n\t\033[33m\033[1mWrong entry!\033[m\n Type 'yes' or 'no'"
    fi