Re: SPF and bouncing

Long ago, Nostradamus foresaw that on Apr 3, Michael Deutschmann would write:

> So, the answer then is "No.  Unlike the non-SPF case, you won't make
> anyone angry.  But there's still a substantial risk of double-bounce,
> which you can avoid by remaining as cautious as if there were no SPF."

What double-bounce?  By definition, there should never be any bounce
to MAIL FROM <>.  If the original sender won't accept the <>, then it
gets logged and goes in the bit bucket (and they never find out that
they mistyped the address - you don't accept DSNs, you don't find out
such things, duh!).  You MUST NOT bounce a message with MAIL FROM <>.