I’ve been using your plugin in my website for a year, and I must say I love it. I created another website a couple of weeks ago, and tried using your plugin after restoring it from my first website, the subscribers are the same. I tried sending 40,000 emails. The first 10,000 emails went without a problem. Then I realized that I hadn’t set the “sender email address/Return path/reply to” correctly, they’ve been set to my first site, so I corrected them to my second site. The newsletter campaign was active, with 10,000 of the 40,000 emails sent.
After that, something strange happened. The emails were shown that they were sent, but I was not receiving any auto-replies at all (very strange), and the percentage of failed messages dropped from 20% to 1% (also very strange). When the campaign was completed, not all of my subscribers received their emails. I tried sending a few other campaigns to myself, I never received the emails despite the fact that the emails are shown as sent. The emails of my website (webmail) work perfectly. Also everything in “STATUS” is set as “OK”. I realized that after 10,000, the emails were either not sent at all, or sent to a very low number of subscribers for some reason.
What do you think the problem might be?