Is there a parameter or a tag I can use to allow users to input only unique values such as the email address through the databound form?

As an example a user's email address can subscribe to the news-letters only one time. If the user enters an existing email address to the databound form it throws an error.

Thanks.

[trendoman]

This? viewtopic.php?f=4&t=11513&p=30704&hilit=validator+unique+email#p30704