Alex could probably answer this better than me, but the first solution that comes to mind would be simply deleting the entry immediately after the emails have been sent.
If you're familiar with PHP you can use the gform_post_submission hook to get the ID of the entry that was just created and then you can create a custom version of the GF function delete_lead (found in forms_model.php ~ line 512). The reason you couldn't simply use the GF version of the delete_function is because it does a permissions check and most users who submit the form would not have sufficient permissions to delete a lead.
Hope that helps.
Posted 11 years ago on Thursday August 12, 2010 | Permalink