diff --git a/target/scripts/helpers/database/manage/postfix-accounts.sh b/target/scripts/helpers/database/manage/postfix-accounts.sh
index ad91982f..efaf05f3 100644
--- a/target/scripts/helpers/database/manage/postfix-accounts.sh
+++ b/target/scripts/helpers/database/manage/postfix-accounts.sh
@@ -74,6 +74,10 @@ function _arg_expect_mail_account
 function _account_should_not_exist_yet
 {
   __account_already_exists && _exit_with_error "'${MAIL_ACCOUNT}' already exists"
+  if [[ -f ${DATABASE_VIRTUAL} ]] && grep -q "^${MAIL_ACCOUNT}" "${DATABASE_VIRTUAL}"
+  then
+    _exit_with_error "'${MAIL_ACCOUNT}' is already defined as an alias"
+  fi
 }
 
 # Also used by delmailuser, setquota, delquota
diff --git a/target/scripts/helpers/database/manage/postfix-virtual.sh b/target/scripts/helpers/database/manage/postfix-virtual.sh
index c4108f90..c847d630 100644
--- a/target/scripts/helpers/database/manage/postfix-virtual.sh
+++ b/target/scripts/helpers/database/manage/postfix-virtual.sh
@@ -25,6 +25,10 @@ function _manage_virtual_aliases
   case "${ACTION}" in
     # Associate RECIPIENT to MAIL_ALIAS:
     ( 'update' )
+      if [[ -f ${DATABASE_ACCOUNTS} ]] && grep -q "^${MAIL_ALIAS}" "${DATABASE_ACCOUNTS}"
+      then
+        _exit_with_error "'${MAIL_ALIAS}' is already defined as an account"
+      fi
       _db_entry_add_or_append "${DATABASE_VIRTUAL}" "${MAIL_ALIAS}" "${RECIPIENT}"
       ;;