The administrators of a site are unlikely to see their own email digest as it appears in an actual email client. The problem with this is that email clients are very inconsistent in the way they render an email. Either the digest could be automatically sent to admins, or there could be a button on the ‘Preview Digest’ page for sending the digest to the admin.
I have another user with an email like
email@example.com that I rarely log in with to check behavior for non-admin users. This user usually receives a digest so I have some visibility into what is getting sent without having to use the preview feature much.
That’s a pretty neat idea - really you could just have a field on the digest preview to put in any email address and hit send. I like the way mailchimp handles this but we don’t really need such a sophisticated interface.