Q:

Grails Spring Security use email to login

My User domain class extends SecUser. 
User has a property 'email'. 
Spring security uses SecUser's 'username' to login. 
I need to use 'email' to login.  Is there a way to do this? 
Edit (from the accepted answer):
I deleted SecUser's username property and added email property. 
Then I added this line to Config.groovy:
grails.plugins.springsecurity.userLookup.usernamePropertyName = 'email'

A:

RTFM my friend :)
http://grails-plugins.github.com/grails-spring-security-core/docs/manual/guide/single.html#4.1%20Person%20Class
userLookup.usernamePropertyName 'username'  User class username field

Add to Config.grooy:
grails.plugins.springsecurity.userLookup.usernamePropertyName='email'

newer versions of grails are using a prefix of
grails.plugin.springsecurity instead of  grails.plugins.springsecurity

