[plug] [OT] Bizarre BigPond POP3 Problem

[ryan at is.as.geeky.as]

Okay this is not a Linux question, but the tools for the job are ... and
I'm hoping someone has as many regular bigpond email problems as I do :)

- fetchmail runs every 5 minutes from a Debian server to check 13 email
  accounts from mail.bigpond.com
- that is 13 'serial' connections - there are never 2 simultaneous
  connects to invoke restrictions from Telstra's end - right?
- ONLY the 13 users that are in the fetchmail runs and ONLY when checked
  from this IP get denied as follows (at least once in every 3 fetchmail
  runs):

------8<----snip----8<------
wind-tunnel$ telnet mail.bigpond.com 110
Trying 144.135.24.9...
Connected to mail.bigpond.com.
Escape character is '^]'.
+OK POP3 server ready (identifier 48/3178118)
user someone at somewhere.com
+OK please provide a password
pass <hidden - can be correct or incorrect>
Connection closed by foreign host.
------>8----snip---->8------

- there has been a 41% failure rate since 1:30 AM this morning - before
  that it was 0% from September 2.
- change the IP of the server - works fine
- check some OTHER email account not in the fetchmail list (there are
  about 60 of these) from the bad IP and it works fine.

Telsta seem to have blocked those 13 users from checking via that one IP
(at random times) - does anyone have any explanations that I can't think
of?  

In Telstra Support Language(TM) I have an Outlook Express client
checking 13 bigpond accounts every 5 minutes from a static IP - That is
the same thing to the POP3 server isn't it?

I'm awaiting the Telstra responses - so far I've only got the standard
'no problems with our mail server' response and from past experiences
I'm hyperventilating (_really_ not holding my breath).

Ryan