Can't send preview email from e-Newsletter

I'm getting an error when I try to use the "Send Preview" function in e-Newsletter. I'm guessing my email settings are entered incorrectly. Trying to send using a Gmail account (gobooklets@gmail.com) to a Gmail account (eric.s.townsend@gmail.com). Please advise.

Here's the error language:

Mailer Error: The following From address failed: gobooklets@gmail.com : MAIL not accepted from server,530,5.7.0 Must issue a STARTTLS command first. wt5sm42528254pbc.38 - gsmtp

<p>SMTP server error: 5.7.0 Must issue a STARTTLS command first. wt5sm42528254pbc.38 - gsmtp

</p>
<p>SMTP server error: 5.7.0 Must issue a STARTTLS command first. wt5sm42528254pbc.38 - gsmtp

</p>