Milter-greylist

> Below is the log which I happened to be watching with a tail  -f.   Is
this 
> an anti-greylisting strategy? It continued for the full 5  minutes that I 
> have greylisting set for and then it was gobbled by Spam  Assassin so I 
> don't suppose it really matters.  I wonder if it would  continue for hours

> if I had greylisting set up like that.

  That looks like your typical maliciously clueless cable company.  They've
decided that a Temp Failure means they should hammer your server into the
ground until it becomes a Permanent Failure or you accept their spam.