Using something like:

```python
class GroupMembershipAdminResource(resources.ModelResource):
    email = fields.Field()

    class Meta:
        model = GroupMembership

    def dehydrate_email(self, groupmembership):
        return '%s' % groupmembership.userprofile.email
```

seems to work file. Fell free to ignore this comment, if this is something that you don't need.