Sending Email on Object Property Value

Hi, I am trying to send Email, in my case I have document object which has one property called "Last Date",and I run workflow for the same, so I want to send mail before 1 day of "Last Date" property value, so is it possible to achieve it? or how can achieve this? also How to configure SMTP? at the time of installation I keep it as queue, so is there any guide to configure SMTP to send mail.