I cannot reproduce this issue.
I have never written code to explicitly create a post from the plugin, in fact, searching for any instance of _post
in the code [1] returns nothing related to the “create” or “insert” functions which are the ones used to insert data into the posts table. Even more, the plugin doesn’t stores any data in the database, instead it uses flat files to prevent it from messing around with the database.
I believe you have another plugin installed that is intercepting emails through the wp_mail
action and creating temporary posts for any reason, I know many plugins/themes do this as it is the only good available option to store data in WordPress. However, due to a bug the posts are not being deleted by the plugin/theme that is inserting them into the database. Then, in addition to another bug in the theme that you are currently using, the temporary posts are being treated as a normal post/page and displayed to the visitors rather than ignoring them via the post-type.
However, this is just me speculating, I don’t know how your website works.
Please share more information about your website, list the additional plugins that you have installed, which theme is activated, and any other information that you consider relevant. Once I can reproduce the problem I will promptly fix it.
[1] grep -rn "_post" -- src/*.php