From: http://support.google.com/a/bin/answer.py?hl=en&answer=176600
[box type=”info” icon=”none”]If your printer, scanner, or application can be configured to send SMTP messages, you can configure it to send mail using the Google Apps mail servers.
You can connect to the Google Apps mail servers using SMTP or SSL. If you connect using SMTP, you can send mail to any Gmail or Google Apps users; if you connect using SSL, you can send mail to anyone.
If your device or application supports SSL, connect to smtp.gmail.com on port 465 or 587.
To connect with SSL, you need to provide a Google username and password for authentication. Ensure that the username you use has cleared the CAPTCHA word verification test that appears when the user first logs in. We also recommend ensuring that the account has asecure password.
If your device or application does not support SSL, connect to aspmx.l.google.com on port 25.
You must configure an SPF record for your domain with the IP address of the device or application to ensure that recipients do not reject mail sent from it. You must also add this IP address to the Email Whitelist box in your Google Apps control panel. For example. if your sending device sends from 123.45.67.89, add that address to your SPF record without removing the Google Apps mail servers from the record:
v=spf1 ip4:123.45.67.89 include:_spf.google.com ~all[/box]