Peter Westwood

This plugin allows your users to configure a reminder to be sent to them if they haven’t posted in the last n days.
You configure the reminder on your Profile page (or the profile of another user if you have than capability)
It is in the Personal Options section and called Blogminder Threshold

PJW Blogminder

This plugin allows your users to configure a reminder to be sent to them if they haven't posted in the last n days.

Hefin Dsouza

The WPApps Draft Notifier plugin offers a hassle-free way to keep track of your forgotten or outdated drafts in WordPress. It automatically sends email notifications to site admins, authors, or both, making sure that no unpublished content is left behind.
Whether you are managing a small blog or a large content-heavy site, this plugin helps you maintain a smooth editorial workflow by staying on top of your drafts.
Key Features:
<ul>
<li>Automatic email notifications about old drafts</li>
<li>Customizable email templates with a built-in WYSIWYG editor</li>
<li>Set notification recipients to administrators, authors, or both</li>
<li>Configurable draft age threshold before notifications are triggered</li>
<li>Compatible with all post types, including custom post types</li>
</ul>
Ideal for bloggers, business owners, or content managers who need to stay organized and informed about their unpublished content.
<h3>License</h3>
This plugin is licensed under the GPLv2 or later.

WPApps Draft Notifier

Effortlessly manage your unpublished drafts with periodic notifications and customizable email reminders.

PJW Blogminder vs WPApps Draft Notifier