# Unique Values

As you may know from powermail 1.x you can enforce that every value of a field should only exist once.
This could be helpful if you want to start a competition with powermail and every email should only saved once.

```
plugin.tx_powermail.settings.setup.validation {
   unique {
       # Enable unique check for {email} - every email must be unique on the page where mails are stored
       email = 1

       # Enable a max limit of 3 times for the same entry for {event}
       event = 3
   }
}
```