First, thanks to @cordoval at the #symfony channel for suggesting me to use a symfony2 command to do this.
To use this command you must have the SwiftmailerBundle enabled. More info here.
This is a simple Symfony2 command to send an email, you should add it to a "Command" directory inside your bundle and replace the namespace to fit your project bundle:
The email body is just "test" but you can probably modified it you need to.
Test the new command by running the following:
php app/console capifony:sendemail email@example.com firstname.lastname@example.org subject
Finally, this task will run the capifony:sendemail command after the deployment is complete, be sure to add it to your Capifony script:
Want to learn more about Symfony2 console/command-line commands?