https://meta.discourse.org/t/non-users-cant-post-by-email-even-with-accept-emails-from-anonymous-users-with-no-accounts-checked/39890/4?tl=zh_CN
Non-users can't post by email even with Accept emails from anonymous users with no accounts checked...
Feb 22, 2016 - I have a category with post by email enabled and with the Accept emails from anonymous users with no accounts box checked, yet when non users try to post by...
post by emailnonusersevenaccept
https://lug.wordpress.org/plugins/tags/post-by-email/
Plugins categorized as post by email | WordPress.org Oluganda
post by emailpluginscategorizedwordpress
https://www.wordfence.com/threat-intel/vulnerabilities/wordpress-plugins/post-by-email/post-by-email-104b-unauthenticated-arbitrary-file-upload-via-email-attachments
Post By Email = 1.0.4b - Unauthenticated Arbitrary File Upload via Email Attachments
post by emailarbitrary file uploadunauthenticatedviaattachments