You can configure the usual email-related options:
You can also choose whether the email is added to the Mail Queue or sent immediately.
See the attached screenshot.
Nagios Testing
I schedule the SendMail Workflow Activity to send out an email to a dedicated mailbox on a periodic basis (via the mail queue). In Nagios, I use Nagios::Plugin::POP3 to monitor the mailbox and alert me if the email doesn't arrive. This verifies that the site's mail server is working, that SPECTRE is running, and that the mail queue is being processed correctly.