Check in the option abandoned mailer if you want to enable it.
You can send two abandoned cart mailers, each after a pre-defined time interval after which the abandoned cart will automatically get expired. For eg. in the first time duration you have given interval as 24 and format as hours, then the first mailer will be sent to the abandoned cart user after 24 hours of abandoned cart created.
The system will send two mailers to the users after which the abandoned cart will be deleted automatically.