American Express Settlement Offer Received from Mitchell N. Kay

So I got an unsolicited settlement offer from a company called Mitchell N. Kay, P.C. Law Offices. They are willing to settle my debt of about $6,600 for $1,700. It seems way to good to be true. This is what the letter says:

Dear:
Please be advised this office in concurrence with the creditor, American Express, agrees to accept the amount of $1700.00 in settlement of the above referenced account. This settlement is conditional upon payment being received on or before August 28, 2009. 11 am

As agreed. Kindly make your personal check via telephone service payable to the creditor.

Upon clearance of said payment, as stated above, a letter will be provided to you stating said account has been “settled”. Furthermore this office agrees to advise our creditor to update your credit report accordingly.

If there should be any questions with respect to this matter, please feel free to contact Mr. ____ at the toll free number, 888-xxx-xxxx.

Very Truly Yours:

Debt Collector


It seems pretty legite, but I wanted to get the communities advice on it before I send them payment. Any help would be greatly appreciated.