Sometimes its all about title, right?! So, what is LESS? Well, its my fancy acronym for something utterly simply but very practical. It stands for (L)ocalhost (E)mail (S)erver (S)imulator. Basically its neither email server or simulator in the real sense of word. Its just a little trick you can apply on the “app/code/core/Mage/Core/Model/Email/Template.php” file to compensate for lack of the local email server in your development environment while developing for Magento.
Magento hadles lot of email sending, for various cases such as: Register new customer, New order created, Forgot password, etc. One of the downside of not having email server set in your local environment is that you cannot easily test all the transactional emails Magento handles. So if you are assigned task of lets say customizing email templates, possibly adding new variables to email templates, etc., then you need a good testing ground.