Email Notification: not "instant"!?!

[Eagle_Kiwi]

Hi all,
I have "instant email notification" set on many threads, and as far as I'm aware I get notification every time I should.

But - very often I've already noticed the relevant post myself, sometimes many hours earlier. My point is that often for some reason these "instant" notifications are anything but!

Example:-

Subject: Reply to post 'Academic VoIP project'
Date: 20 Nov 2006 04:53:13 -0600
From: "BigBlueBall Forums" <(censored!)@bigblueball.com>

Dear Eagle_Kiwi,

Dermot has just replied to a thread you have subscribed to entitled - Academic VoIP project - in the Yahoo! Messenger Support forum of BigBlueBall Forums.

This thread is located at:
http://www.bigblueball.com/forums/ya...-new-post.html

Here is the message that has just been posted:
***************
I guess this is the homepage of the school eagle.

Fairleigh Dickinson University (FDU) (Fairleigh Dickinson University (FDU))
***************

THIS post of Spike's was posted at 11:53pm last night (my time). I've just now (11:50am) received my email notification of it - 12 HOURS later!!?!

Received: from mail2.zoneedit.com (mail2.zoneedit.com [216.40.250.211])
by dbmail-mx3.orcon.co.nz (8.13.6/8.13.6/Debian-1) with ESMTP id kAKMoaU6010991
for <(censored!)@orcon.net.nz>; Tue, 21 Nov 2006 11:50:40 +1300
Received: from hester.totalcontrol.host (a4.63.344a.static.theplanet.com [74.52.99.164])
by mail2.zoneedit.com (Postfix) with ESMTP id 0F0A037FA0E
for <(censored!)@eaglekiwi.com>; Mon, 20 Nov 2006 14:27:11 -0500 (EST)
Received: (qmail 29535 invoked by uid 48); 20 Nov 2006 04:53:13 -0600
Date: 20 Nov 2006 04:53:13 -0600
To: (censored!)@eaglekiwi.com
Subject: Reply to post 'Academic VoIP project'
From: "BigBlueBall Forums" <(censored!)@bigblueball.com>
Auto-Submitted: auto-generated
Message-ID: <200611201011.2d1063565560@www.bigblueball.com>

Those headers (converting everything to GMT) show:
20 Nov 10:53 - Spike's post to BBB
20 Nov 19:27 - Email from hester.totalcontrol.host to zoneedit (my redirection address)
20 Nov 22:50 - Email received by me (@orcon.co.nz) from my zoneedit.

Well, I must wear the blame for 3.5 hours delay, between my zoneedit redirecting service and me (odd, generally this is only about 5min max) - but the other 8.5 hours before hester.totalcontrol SENT it is puzzling.

Does anyone else notice this effect - and/or have any useful answer (apart from just "Be Patient"!)

(I've rechecked my BBB settings, and they're definitely all "instant" and not "daily" notification).