Note: This artical is only applicable if you would like send an email via the standard Salesforce functionality.
This basically means that you would like to send an email directly via a Job application or via a Candidate; without taking a step.
All users can customize their personal email settings.
Setup | Personal Setup | E-mail | My Email Settings.
Here you can:
1. Customize how you would like your name to appear on your outgoing email.
2. Define your return email address.
3. Decide if you want BCC on emails sent from salesforce.com.
4. Customize your email signature.
If you would like to use the email signature in email templates, merge field can be added in these templates. Find more info here.