Well it is very obvious that P means positive but I am also stumped by the MP.

If you go all the way back to the first page of the feedback that she has left she is very verbose and actually puts Positive.   Occasionally she has obviously left the feedback a bit lkonger and has apologised to the seller for leaving it late.

I too would love to know what the M stands for.....obviously a bit better than just a plain old Positive.