Possible reasons for Abandoned Cart Emails not being delivered in Magento 2 includes,

• Incorrect email configuration (SMTP settings)
• Email deliverability issues (e.g., marked as spam)
• Missing or incomplete email templates
• Inadequate cron job setup for automatic email sending
• Customers using invalid or unsubscribed email addresses

You can use our Magento 2 Abandoned Cart Email Extension to setup abandoned cart email in your Magento 2 store.

Read this guide on How to Configure Abandoned Cart Email in Magento 2 set up Abandoned Cart Email in Magento 2.

Here are the few more resource to help you get most out of this Magento 2 Abandoned Cart Email Extension.

• Abandoned Cart Emails : Best Strategies to Recover the Lost Sales
• What is Abandoned Cart? 5 Easy Ways to Reduce your Abandoned Cart Rate
• How to Boost Sales using Abandoned Cart Email Extension in Magento 2
• Benefits of Abandoned Cart Email for eCommerce Business