Mass Email HTML Customised, How to do it?

Hi guys,

My previous work place were able to log into word press, and they had an option on the left hand side to to send mass email.

The first page allowed you to add a new client by putting in their requirements e.g “the type of house they are looking for, Location, bedrooms, Price and brief description”.(Customised check boxes for all options). After the client was added, the email was sent in mass at a particular time, e/g 3pm.

You also had the ability to add in real estate agents details including Name, Email, Office, and location they specialise in.
So when you add in a clients requirements it would know which agents to send the email too. The email was a HTML email with graphics and pictures.

I wanted to know how this is done through word press? Is it a customised website that sits within wordpress? A plug in? How is this created? I remember having to Log in to word press, but cant remember exact detail. Once I understand how its done, I will then look to pay someone to create this. Appreciate the help ??

Thanks – Ryan