Thanks for your review. Did you try contacting our support by any chance? (I don’t see any threads, but maybe by email or our site?) This is a completely free plugin and, while there may not currently be much documentation, we offer full support of this plugin for free, either via these forums or our website (https://www.etoilewebdesign.com/support-center/).
There are no limits or restrictions in this plugin. You can send as many emails as you want. The only limits would be on your site/hosting end (e.g. if you tried to send to a lot of users at once and your site timed out before sending, or, if, somehow, something happened like your host blocked you for trying to send too many [though I would think that would be unlikely to happen in this case]).
Would you be able to let me know which email send option you were trying to use when it was failing? Did you try any of the other options, such as emailing to a single user, sending a test email or sending to an existing list? What were the results of the different options (e.g. maybe you can send to an individual user, but just not to a list)?
Additionally, I just tested to make sure and the list feature is definitely working, so I’m thinking there is either a hiccup in the way you’re trying to put the list together or some conflict/issue that is specific to your WP install and that is preventing you from getting the list created correctly.
Could you let me know the exact steps you were taking to try and create the list? You first need to click the ADD button and give the list a name. Then you can check the users you want and click the Add Users button, and it will move them over to the right side. Then click Save in the pop-up dialog. Then click Save Changes on the Lists page.