Bin Chen is a busy guy and as a freelancer he gets lots of emails offering jobs. Each type of reply is mostly the same as all the others of that type so it makes sense to automate those replies to reduce time and errors.
Chen uses yasnippet to make templates for those replies. All the normal text is there and he can tab through the fields to fill in the instance specific data. He even has a bit of Elisp to extract the first name of the recruiter from the email address and insert it into the greeting.
It’s a very nice solution and one that can be adapted to work with any type of repetitive communications that you write. It’s easy to set up and integrates nicely with Emacs. Even if you don’t use Emacs for your email, it’s easy to set Emacs up to send email with your normal email address. With OS X, I can have it either pop up the message in the (OS X) mail app or send it off directly.