This module will automatically send a email messages to users who have abandoned their Drupal Commerce carts.
On each cron run the module finds Drupal Commerce carts that have been abandoned (using configurable settings) and that the user has gone to the point in the checkout process to have entered their email address. Then the module will send an email message to the user(s) to remind them that they have a cart, or ask if they had an issue during checkout.
Email messages are fully customizable. Message limits and other options are configurable in the module settings.