Hi @qdhd99,
I’m sorry to hear about it. Please note this is not the normal behavior for the Post Notifications and our dev team can confirm this bug was introduced in the v. 3.99.0 release.
We’re working on a fix and will release it within the next 24 hours. Thank you for your patience with this, and we apologize for the inconvenience!
Meanwhile, if you need to send a new Post Notification email today, please roll back to the previous version 3.98.0.
To do it, please deleted both free and Premium plugins (if you have a paid subscription) and re-install them from scratch.
To re-install the free plugin, go to wp-admin > Plugins > search for the MailPoet plugin and install it.
If you can wait for the fix, please disable your Post Notification emails for now by temporarily deactivating them.
Again, please accept our apologies for the inconvenience.