A recent post bears the subject line:

 > Re: Serbian genocide work of God?

The text contains 80 lines devoted to a defence of the doctrine of
predestination as applied to the salvation of individuals. There is
then a five-line post-script on the Balkans. It is natural and easy
to keep the Subject line of the post that one is replying to, but
when the focus shifts, keeping the same Subject can cause confusion.

This is intended as a general request. The post mentioned is just
the handiest example.