Insolvent estate

What is the name of your state (only U.S. law)? MA

My dad passed recently, and I'm named executrix. At the time of his passing he had less than $1,000 in assets, and credit card debt just under $10,000. After paying funeral costs (above and beyond his $5400 life insurance policy), and other misc costs, his cash balance was in the negative by about $5. I sent a letter to the creditors stating the estate is insolvent and attached a death certificate. I am now getting letters from collection agencies. The will has not been probated, as there are no funds available to pay for it, and no assets in the estate. My dad owned no property, stocks, etc. Do I correspond with the collection agencies or just let it go?
Thank you.

My expertise is in NYS probate, but many states operate in a similar fashion. In NYS a creditor has to file a claim with the fiduciary of the estate. If there are no assets the fiduciary does not have to pay anything. If there is no personal representative, the creditor can petition the court to have a fiduciary appointed (usually the Public Administrator), and then file their claim. The only problem is they still won't receive anything if the estate is insolvent. The creditor is just wasting time and money trying to squeeze water from a rock. In NYS I would say just ignore them. You did them a favor by advising them the decedents dead. If they want to continue wasting resources, let them!

Thank You!