I just tried to reply to a kind soul that had offered some help with the
3.2.1 root errors and got:

----- The following addresses had permanent fatal errors -----

(reason: 554 : Client host rejected: Polish Spammer)

----- Transcript of session follows -----
.... while talking to
>>> DATA

<<< 554 : Client host rejected: Polish Spammer
554 5.0.0 Service unavailable
<<< 554 Error: no valid recipients

I am neither a spammer, nor in Poland but a legitimate UK business with
the same IP address for some years. Where on earth did this response come
from ? It's a bit thick to get branded as a spammer when replying to
someone from this list!