Milan Dinić

<a href="http://blog.milandinic.com/wordpress/plugins/post-to-queue/" rel="nofollow ugc">Plugin homepage</a> | <a href="http://blog.milandinic.com/" rel="nofollow ugc">Plugin author</a> | <a href="http://blog.milandinic.com/donate/" rel="nofollow ugc">Donate</a>
Don’t want to publish all of your posts at once but hate manual scheduling/rescheduling? Post to Queue comes as a solution. You just put posts to queue and they’ll be published automatically when chosen time passes since last published post of that post type. It’s even possible to choose days of the week and hours of the day when those posts will be published.
Post to Queue is like Buffer for WordPress, just better.
It requires that cron runs regularly to be able to publish posts on time.
Post to Queue code is partly based on a code from plugin <a href="https://wordpress.org/plugins/automatic-post-scheduler/" rel="ugc">Automatic Post Scheduler</a> by <a href="http://tudorsandu.ro/" rel="nofollow ugc">Tudor Sandu</a> and a code from plugin <a href="https://wordpress.org/plugins/metronet-reorder-posts/" rel="ugc">Metronet Reorder Posts</a> by <a href="http://www.ronalfy.com/" rel="nofollow ugc">Ronald Huereca</a> and <a href="https://geek.hellyer.kiwi/" rel="nofollow ugc">Ryan Hellyer</a> for <a href="http://www.metronet.no/" rel="nofollow ugc">Metronet Norge AS</a>.
And it’s on <a href="https://github.com/dimadin/post-to-queue" rel="nofollow ugc">GitHub</a>.

Post to Queue

Stack posts to queue and auto publish them in chosen interval and time frame.

<a href="https://milandinic.com/wordpress/plugins/simple-email-queue/" rel="nofollow ugc">Plugin homepage</a> | <a href="https://milandinic.com/" rel="nofollow ugc">Plugin author</a> | <a href="https://shop.milandinic.com/downloads/simple-email-queue-plus/" rel="nofollow ugc">Plus Version</a>
Simple Email Queue is a WordPress plugin that is used to pass restrictions set by your host on number of sent emails in given period.
This basic free version is only useful for developers that can extend it and use it in their code. If you want to use it in full capacity, consider getting <a href="https://shop.milandinic.com/downloads/simple-email-queue-plus/" rel="nofollow ugc">plus version</a>.
<h3>Usage</h3>
First, you need to set what is maximum number of emails that can be sent in a given period. By default, it sends 10 emails in 6 minutes. This means that if you want to send 15 emails in 6 minutes, only 10 emails are sent while rest 5 emails are put in queue and sent in the next period, after 6th minute has passed.
You can change this limits by using filters from you code. Filter <code>simple_email_queue_max</code> is used to set maximum number of emails that are sent in period. It expects positive integer to be passed.
To change period length, you can use filter <code>simple_email_queue_interval</code>. It also expects positive integer to be passed but please take care that this number is of seconds, not minutes (for example, if your period is 30 minutes, you would pass <code>1800</code>).
Different hosts use different limits. Please consult your host’s documentation or support to find this out.
If you want user interface in your admin area, use <a href="https://shop.milandinic.com/downloads/simple-email-queue-plus/" rel="nofollow ugc">plus version</a>.
To use this limits, you need to use function <code>simple_email_queue_add()</code> instead of built-in function <code>wp_mail()</code>. Both accept same parameters. 
Emails that are sent using <code>wp_mail()</code> function are not sent using queue and are not counted for limits. If you want that all emails are sent using queue, even those sent using <code>wp_mail()</code> function, use <a href="https://shop.milandinic.com/downloads/simple-email-queue-plus/" rel="nofollow ugc">plus version</a>.
And it’s on <a href="https://github.com/dimadin/simple-email-queue" rel="nofollow ugc">GitHub</a>.

Simple Email Queue

Put email in queue and send it one by one, by limits.

Post to Queue vs Simple Email Queue