John Woodstock wrote in a message to Tony Langdon:


 TL> Something he said suggested he has a dynamic IP, so mail would most
 TL> likely be POP3 (how do you SMTP connect to a changing IP address?)

 JW> If the ISP updates DNS as you log on, then you resolve to the
 JW> name.. It is fairly straight forward..

What ISP does *that*? 

1: You gotta keep the caching times down to a *very* small value,
   so that whenever someone looks up that MX, if it's more than
   a few minutes they have to refresh it again.

   Contrast this to the default of _1 week_ for domain expire
   times..

2: That requires restarting the name server on every login.  
   Only practical if that name server is not servering several
   hundred domains, as it does take a while for it to
   come back to life.
  
   Alternately, one *very* hacked version of a name server,
   that gets info on the fly.

I looked into this very thing a couple of years ago, never
found anything suitable.  Seriously speaking: any ideas you
have on where to get info would be great.  


cheers,
 jason