Send Email notification not working in Opencart2.x(2.0.1.1)

Hello friends,

We are using OpenCart (v2.0.1.1) for our site. We have installed extension called Layaway-Payments-Layby-Installments for Payment System. It's working fine with the site but issue is, it is having feature of Send Email notification which is not working. According to extension, if we set Pay By Date, an email notification is sent before that date which is not working currently. According to the support team, Opencart 2.x has an internal bug due to which, mail protocol doesn't work.

So basically we want Send email notification working in same version.
Any help will be appreciated!!!

Thanks