I've tried all settings that were mentioned in regards to multiple post notifications being sent to subscribers, however for some reason, some of the notifications are going to random subscribers over 1000 times.
In a couple of cases, I disabled the plugin, which seemed to have stopped the mails being sent out. Once I re-enable the plugin, it takes a few minutes to turn back on, and then some users receive more (hundreds, thousands, etc).
Our host is no help, since it is on a shared server environment. I asked about mail queues to see if there is some sort of backlog of emails.
The worst part of all of this, is that it was working fine for months, and we even installed it on a different site which does not have any of the issues.
Unfortunatly I can't afford another 1000 emails being sent out to customers, so I am abandoning this plugin, however if anyone has any advice, I would still like to try to troubleshoot it.