Dan Collis-Puro

This plugin allows users of subscriber- or greater access to subscribe to categories of posts on your wordpress blog. It is probably most appropriate for small to medium sites.
Users can:
<ul>
<li>Choose whether they prefer HTML or text-only email,</li>
<li>Control on a category-by-category basis whether or not they get messages immediately or in a daily or weekly digest.</li>
<li>Control which categories they subscribe to.</li>
</ul>
Site administrators can:
<ul>
<li>Modify reply-to, from, and BCC addresses.</li>
<li>Modify user subscriptions on a users profile page.</li>
<li>Set basic parameters for delivery – how many messages to send at once to avoid usage complaints on shared hosting, for instance.</li>
<li>Bulk edit category subscriptions from the users list.</li>
<li>Exercise complete control over text and HTML templates.</li>
</ul>
Other notes:
<ul>
<li>Scheduled posts are only sent out after the wordpress backend actually publishes them. Put more simply, they work as expected. Be sure wp-cron is running correctly.</li>
<li>Admins can set a “send delay” parameter to allow last-minute edits before sending out a message.</li>
<li>If a message is unpublished after being published, message sending will be aborted. Messages sent already are – well – sent already. We can’t travel back in time (though that’d be a great 2.0 feature). This ensures that old posts needing minor edits don’t get sent out again as updates.</li>
<li>Only messages published after the date of installation are sent out.</li>
<li>Category hierarchy has no effect on subscriptions. If you subscribe to a parent category, you ARE NOT automatically subscribed to its children. This may be integrated into future releases. We may also allow for the subscription to tags or custom taxonomies in future releases.</li>
<li>Bounces ARE NOT handled by this plugin. You can, however, set the “reply-to” and “from” addresses to allow you to collect them in a logical place.</li>
</ul>
Speaking of cron, if you have a low-traffic site (say, for an intranet), you may find that your messages aren’t delivered in the time frame you’re expecting. This is because wordpress scheduled tasks are fired off by visitors to your website – so if you don’t get a lot of traffic, your scheduled tasks won’t run frequently. You can manually create a cron job to hit your wp-cron.php file, something like:
*/15 * * * * wget -q –post-data=”foo” http://www.example.com/yoursite -O – > /dev/null
Remove the “-q” switch above when you test this manually to ensure the request returns a “200 OK” response.
TODO:
<ul>
<li>More template tags.</li>
<li>Better bulk editing features.</li>
<li>Queue management / statistics.</li>
<li>A better template editing interface.</li>
<li>Better debugging – e.g. the ability to send example messages.</li>
<li>More flexible task scheduling.</li>
</ul>
<h3>More Documentation</h3>
See the “Category Subscriptions” options page under your Settings menu. Template tag documentation lives there.
<h3>Other</h3>
This plugin is licensed under the same terms as WordPress itself.
Copyright 2011, The President and Fellows of Harvard College

Category Subscriptions

Allow registered users to subscribe to categories giving them control over delivery times (e.g. daily or weekly digests) and format (html or text).

webheadcoder

What happens if WP-Cron stops working?
WordPress, Themes, and Plugins would never know if a new version is out. You could login to your website everyday for months, and never see any notices about updates. If you’re not careful you’ll soon have an out of date WordPress installation susceptible to hackers. Scheduled posts would never get published, auto drafts never deleted… you get the picture. Your website would crumble up and die.
Use Woocommerce? Subscriptions? Customers would never get billed again! Sessions would never be deleted. Scheduled sales would never appear. Your website would become bloated while giving away subscriptions for one time payments.
WP-Cron is important. So make sure it keeps working.
Think of this plugin as insurance, but free. WordPress, plugins, themes, and servers are all moving parts that can be updated at anytime. You can’t guarantee any of these changes won’t break your website in some way. While it’s not likely WP-Cron will stop working, if it does, you better know about it.
Every 24 hours this plugin automatically checks to see if WP-Cron is still able to run. Obviously, it does not depend on WP-Cron. Instead it sets its own transients that expire over 24 hours. Whenever the transient expires it checks to make sure WordPress can run WP-Cron. If an unexpected error occurs the you’ll get an email.
In addition to checking if WP-Cron CAN run, this plugin now logs all hooks running with WP-Cron and if they fail or complete. You’ll be able to see what ran, when it ran, how long it took, and if it completed.
For your convenience The WP-Cron Status Checker is displayed on your WordPress admin dashboard. The status page is accessible through the Tools -> WP Cron Status side menu.
Know when WP-Cron doesn’t complete
When a WP-Cron hook fails you’ll get notified soon after. A hook “fails” when it takes longer than 5 minutes to complete. You’ll get an email within 24 hours (or based on the plugin’s settings) to notify you of any failures.
Sometimes a plugin runs some code that abruptly exits the process and there is no way of knowing when it stopped. WP-Cron Status Checker does it’s best to detect this type of code. If it’s caught, the elapsed time is not recorded and you’ll see “N/A” with an “Incomplete” status. Other times when it’s caught you’ll see an “Exit” status which is considered complete. <a href="https://webheadcoder.com/wp-cron-status-checker/" rel="nofollow ugc">Please see the plugin page for more on completion statuses.</a>
PRO Version 
The PRO version removes the 3 log limit and lets you choose to keep logs longer and email more frequently. Please see more on the plugin page: <a href="https://webheadcoder.com/wp-cron-status-checker/" rel="nofollow ugc">https://webheadcoder.com/wp-cron-status-checker/</a>

WP-Cron Status Checker

I know I created this plugin, but I am also using it and it has warned me WP Cron stopped working.  I'm not sure what the error was.  WP Cron just stopped working for a short while and then started working the next day right before I contacted the web host.

Caught an error

I debug WordPress websites for a living and a stopped, paused or failed cron is often a problem. I use this plugin to help in the process. Thanks to the dev!

One request. At first, it was very hard to find where to find the status (it's a widget on the dashboard btw). It would be helpful if this was mentioned somewhere in the description of the plugin (unless its there already and I missed it). 

Cheers!

Very handy tool in my debug tool kit

This is an easy way to check if WP-cron is enabled and jobs are actually running. Don't let the relatively low number of active installations mislead you, I suspect many people may use this plugin just like I did - install it just to check WP-cron is doing ok, then remove the plugin again.

My only criticism is that I had expected to be able to view the WP-cron status on this plugin's settings page, instead I had to look for it in the Dashboard.

Good tool to check WP-cron


I installed by mistake, intending to use a simple tool to monitor and log WP-Cron activity. It appears, this is now another freemius plugin which seems to me to be a bait, because description and screenshots are not accurate and up to date.



To use this plugin is now required to give all your personnal data or to register/subscribe. This shouldn't be required for such limited functionality plugin. An unnecessary and intrusive step for something as simple as viewing cron logs



Thankfully, better alternatives exist. Installed by mistake, uninstalling by will.


Almost a bait because it requires personnal data

If WP-Cron runs important things for you, you better make sure WP-Cron always runs!

Category Subscriptions vs WP-Cron Status Checker