Yes, the registered users have been subscribed to the blog post categories. I have also tried both daily and once-per-post mailings with no difference in result. I have changed the admin email address to an on-site address (although previously an external email address was used with no problems). I have made sure that the tickbox on the post pages is unchecked by default. I have created a page on the site for the subscription code to reside (even though I understand that is no longer necessary). No, I have not tried setting the email to “1” because I don’t know who that email would go out to and have no way to check. However, as I said before, the server will send email to only public subscribers (which are almost all people I have manually subscribed)–this to me says that my emails are not being blocked at the server level. Also, when I couldn’t get the plugin to work, I manually sent a notification to all subscribers via the website email. I bcc’d all of them. If the account were under suspicion, I’m assuming that wouldn’t have been possible. In addition, prior to my taking over the site, mails were sent to the same number of people as now.
I’m further frustrated by the fact that I run this plugin on two other sites and it works perfectly for both subscribers and registered subscribers. To me, this is beginning to look like some sort of database corruption, either with the member list or the database itself. I’m not sure how to fix this since my predecessor did not pass on any database backups he might have done. Plus, I’m not sure I’d want to restore to previous point even if I could–the site has been massively redesigned in the last month. Other than corruption, it could be a server issue–the other two websites are with a different provider. (This one runs on iPower, the other two run on Total Choice.)
I should say also that I’m running version 6.4 of the plugin and wordpress release 3.2.1. My problems with the plugin started before the WP upgrade, so I’m pretty comfortable assuming that it’s not part of the issue.