I was wondering about something similar yesterday; the feasibility of a provider truthfully indicating receipt whilst staying within the confines of the law.

For a 'regular' warrant, a provider can "confirm" or "deny" being served. Presumably they can "deny" being served a secret warrant if one hasn't been served, because the terms of a secret warrant presumably only require them to decline acknowledgement if they've been served, in which case they could "neither confirm nor deny", couldn't they?