I think a bar code scanner/OCR kind of functionality could also be useful. If the other person does not have your app and isn't comfortable about sharing their

I think a bar code scanner/OCR kind of functionality could also be useful. If the other person does not have your app and isn't comfortable about sharing their email address, they can just photograph your card. Later they can download your app if interested and the app can use OCR or bar code scanning to identify the original e-card.