Sending email with Javamail from a script without a password

I have a script that runs a Java program to run some tests every night. It needs to email out the results of the tests, using JavaMail and a Google apps account.

How do I authenticate with Gmail (through the JavaMail API), without storing the password on the machine that runs the nightly tests? Can I get some sort of an Gmail authentication key that is valid for, say, a month? I don't mind refreshing the key every month, but don't want to keep the password on the test machine.

Google email accounts cost money so I would prefer not to create a new account just to email test results out.