I am having a similar problem. As far as I know, it has been working fine until I downloaded the most recent version 1.5.4. I always have my own email address so I can see that it is sending out the post notifications. This time, I didn’t get a notification. I checked with 2 of my subscribers, and one did get the notification, but the other one didn’t. It says in the log that all of my subscribers were successfully sent the email, but obviously that didn’t happen. Since I have 9 subscribers, it can’t be a limit of emails.