I left US with a debt of around 12 k $. Kept paying it for 4 years ans was able to bring it down to 4 k. ( don’t ask how much fees they put on it, how much APR they raised, simply because I failed to pay on time once). Now the thing is that I lost the account which I used to pay this credit card about a year ago and stopped the payments as it was impossible to transfer the monthly payments from here on time each month ( and couldn’t pay in full). Besides I did not feel moral obligation to pay them any more ( I paid much more than what the initially approved APR would have allowed to pay off the debt).

So, now I receive a letter in email by a collection company asking me to pay 5.5 k . The funny thing is that they did not send it to the email the original creditor had on file. My guess is that they probably googled my name and found it. Should I reply them and ask for validation? Do they have any means to serve me a summon? How do they prove to the court that the summon has been served. What if they just post it on my previous address in US and claim that it has been served? Can they serve the summon to an oversees address? Please reply.