Not to be too practical, but have there been any real problems resulting from failure to deliver "stuff," electronically or otherwise?
How is mailing something, without a return receipt (and God forbid anyone is actually doing return receipts), or hand delivering without a signed receipt, and better than an email blast to all employees (without return receipt).
Admittedly I don't deal with any plan that has 1000 participants, let alone 20,000, but I only see this becoming a real issue if there is some kind of pattern of secrecy and/or deceit. As nasty as the DOL can be, I don't see them dropping the hammer just because 5 participants' SARs got lost on a server.