General help

I have a new LAMP (Ubuntu) server and a new Moodle 3.0 installation and I'm trying unsuccessfully to get Moodle to send e-mails through our Google Apps account. When I try to send an e-mail (via a news forum or Quickmail or the Mail Test app), no e-mail is sent and I get very minimal debugging information even though I have debugging set to Developer, and "debug e-mail sending" and "display debug messages" set to On.

The Mail Test app, which I thought was supposed to give me error details, says only "Emailing failed. The test email message could not be delivered to the mail server. Check your Email settings." 

Quickmail says, "Could not email: Kimber Warden (kimberwarden@skonline.org)" and gives this debugging info:

Notice:  Undefined property: stdClass::$id in /var/www/moodle/lib/moodlelib.php on line 5684

The mail forum gives no indication that anything is wrong at all. It says, "This post will be mailed out immediately to all forum subscribers."  But no e-mail is sent.

Given that I have so little information to go on, what should I investigate? Do I need to configure the server in any special way?

I have these settings in Plugins->Message Outputs->Email:

SMTP host: mail.skonline.org:465

SMTP security: SSL

SMTP auth type: LOGIN

SMTP username: myusername

SMTP password: mypassword

Thanks so much for any help you can offer!