If you haven't heard back from them, that is a very bad sign.
However looking at what they are offering, that too does look very good either.
They buy copper cents for 1.25 cents and you pay shipping. So $100 face value worth of pennies that wieghs about 68lbs in a US flat rate medium box and costs $11 to ship. They will pay you $125 and you profit $14. If your penny boxes are 20% copper than you will need to search/ryedale $500 (20 boxes) to find $100. You will need to dump $400 worth of Zincolns. That seems like alot of work for not a lot of money.
Unless you are not interested in copper cents and you want to search a large volume of pennies for wheats/IH/KGV/KGVI etc and selling the copper lincoln memorials is just a way for earning some profit on a byproduct.
If you want to sell your copper pennies, I would suggest selling locally via Craig's list and avoided shipping fees that eat up a lot of profit.