This can happen on some hosting providers that send email on your site’s behalf, but not all providers. It’s still a bit unclear exactly what this only happens to on some hosting environments and not others. It’s possible that it has something to do with these hosts’ complex and proprietary caching systems and how they interact with WPCron as well their built-in transaction mailing systems.
Either way, we know that it has the potential to happen on the following hosts:
To overcome this issue, we recommended bypassing your hosting provider’s transactional email system by utilizing a plugin that can send site emails through SMTP (using your email provider) or through one of the following transactional email providers and their corresponding WordPress plugins:
- Postmark (Plugin) – Our personal favorite – we use this for all of our site emails
- SendGrid (plugin) – Popular transactional email provider
- WP Mail SMTP – Setup your Gmail or Outlook email providers to send emails on behalf of your WordPress site
- Mandrill (plugin) – For Mailchimp Customers only, so if you’re a user of Mailchimp this is a great option because it’s free for you