I was able to get that rare DX in Mississippi on 6m just now on FT8.  I had tried many other modes including SSB in the past with other hams with it being just a one-way contact, but nothing else since email or landlines don't count for the reverse.  

This cleared out a Grid Square that has eluded me for years.  I now have just one left East of the Mississippi River up in the Northeast that's mostly in Canada wastelands.  I still need about 15 in the desert areas of the west and a couple along the California coast line that are 99% water. 

I know it's not really DX, but for FFMA, it might as well be.  BTW, he's already confirmed it on LoTW.