Automatic e-mails from this site not all coming through
Since quite recently, the site has stopped sending all of the forum content I subscribed to. It's isn't related to the fact there are fewer posts lately.
They used to be forwarded by e-mail every few hours or so and contained all of the content posted by members. Now the e-mails do not cover all posts.

No reply emails
I have been getting as many as 6 copies of the same emails from DAG and whilst its posssible to keep going through and deleting the duplicates, I wondered if there was an easy way to avoid this.
I have checked my "subscriptions" but there is nothing there that I can see that should give rise to the emails being repeated.
Repeated emails (e.g. Strategy Team updates)
The reason for repeated emails is a bug in the mass contact module that we use to send out "announcements" - the bug is discussed here: http://drupal.org/node/359930. This is a separate mechanism from that used for subscriptions, the latter, as far as I know, is working correctly.
So, there is no immediate solution available to the repeated emails. There are alternative approaches to providing "mailing list" functionality, and I already have a loose plan to implement Mailman which is pretty much the de facto standard (within the Open Source world.) In the meantime, please grin and bear the repeated emails.
Notifications/subscriptions
I'm not sure, but I think notifications may have been broken during Drupal upgrades, as I am seeing a similar problem on another unrelated Drupal site. I need to investigate, or perhaps just wait for a solution to arrive from the Drupal folks.