--On Sunday, 18 November, 2007 18:37 -0600 Dave Crocker
John C Klensin wrote:
"Four" is in the spec because it is a plausible compromise
without getting bogged down in the details of multiple
countries and cultures and because, if one does get that
involved, one will often come up with four anyway.
As I recall, there was also an empirical basis for this, based
on thinking about the notification "spikes" that were observed
over some years.
For obvious and reasonable reasons, one can strongly argue for
the time-out to be 1, 2, 3, 4, 5, 7 and even 10 days. The
latter are too long for effectiveness and the first few cause
too many false notices.
That leaves, perhaps, 3, 4 and 5 to debate about and 4 does
jump out as a reasonable compromise, doesn't it?