u/Basic_Connection8356

I sent my first five postcards ands after reading some posts on here I think I made a mistake with postage. I live in the USA and all cards were sent over to Europe. I only did one regular stamp not knowing they would need at least $1.70 worth of postage. What are the chances these people get their postcards? Should I resend them? I didn’t put my return address since I heard it messes with the sorting. What should I do???