...which basically suggests that you were correctly charged. Virgin's systems didn't adequately explain that you'd sent your message to an email contact instead of a phone contact. Presumably that wasn't your intention?
Your daughter sent a text message to a person from her contacts list.
She chose the wrong contact - and ended up sending it to the person's email address instead of their mobile number.
The handset converted it to MMS and virgin sent it through a server which processes "text to email".
Your daughter is charged MMS rate. The person received your daughters message on their email client. The bill shows what appears to be an American number but is just an internal reference for the conversion computer.
That's my understanding of what's going on. It's easy enough to test - get your daughter to send you a text to your number, then get her to send it again to your email address. Then look at her bill.
My mobile is with O2, but when I first got it I had the same problem of being charged for photo messages that I had not sent. It was something to do with texts being converted to picture messages for reasons I never fully understood. I asked if this facility could be turned off, and it could. Now on my account it shows 'Remove multi-media messages - enabled'. I have had no problems since. I would ask Virgin to turn it off for your daughter.