How to pay off a blacklisted AMEX debt?

[Anonymous]

Hey everyone, 

I burned AMEX back in 2012 for $2100 and really want to get back in with them although unsurprisingly I'm blacklisted (tried to get added as an AU to no avail). I received an settlement offer in the mail to pay off 60% of the total debt over a 24-month span from the following contact info: 

American Express 
P.O. Box 6985 
Buffalo, NY 14230-6985
1-855-618-2435

Now upon researching I can't tell if this is a third-party branch or actual in-house AMEX collections, I'm getting mixed findings online when I search it up by people saying it's not them to saying it is them. To sum it up though, my questions in a nutshell are:

• Is the above the actual AMEX/has anyone received a settlement offer letter from this address? Just nervous that if I accept it won't affect my placement on the blacklist.
• If it does happen to be AMEX, would it possible to be removed from the blacklist/regain card membership if I pay the settlement?
• As it's likely better to pay it off in full, can I call American Express directly to do so and would that increase my chances for getting back in versus accepting that settlement offer? What if they say it was sold to a creditor? Not sure on the etiquette and how realistic trying to settle a 6 year old debt with them directly is.
• I used to receive the Optima/Oasis invite letter, I received one maybe once a year but haven't got one as of 2016. Would this be a way to go, and can I call to request the invite again or do I have to ride it out? My worry is I won't receive the invite in the mail ever again.

Any help would be much appreciated! Officially starting my journey to mend my relationship with AMEX and really hope it pans out!

[Cherekas]

If your true intentions are to pay to get back in, I would call the number and question if they are in fact Amex or an outside collector. As old as the debt is, I would either settle or PIF and question if I would be able to become a member again. You have nothing to lose at this point. 

[bourgogne]

no such thing as `outside' with amex, they retain 100% of their debts.  settle in full or less will always = ymmv as far as being able to do business with them again.