You have three options: 

1. Go to Candidates, click the three dots by a chosen candidate and select Send message.

NOTE: to use this option, you first need to integrate your mailbox with Traffit.

2. Open a candidate profile, hover over the envelope symbol in the upper right corner of the screen and select: Send email to candidate.

3. From the list of candidates in a job - to a particular candidate or to a multiple candidates at a time:

You can compose each e-mail message yourself or using e-mail templates: