An email (and/or SMS message) goes out tot he customer in v2.1 emails called “There’s a problem with your shipment”, or thereabouts, I believe. It would be nice if you could see who those went to in the ‘sent’ section/stats at bottom. Right now I"m totally drawing a blank on how you set certain system emails to send a copy to the admin. I get them for some system emails but not others. If I could get a copy of those it would tell me there’s some issue.
For the SMS message you can see these in the outbound queue, etc. Not true of emails though.