PHP script results in "Error code: 701"

Attempting to run a PHP script (a form to send email), and every time I use it, I get this message:

An error occured. Please contact the site administrator.

Error code: 701

This same script works fine on other servers, so I’ve reached the conclusion it’s something with Dreamhost’s config.

Any suggestions?

701 isn’t a standard PHP or SMTP (email) error code, so I’m guessing that’s being generated by your script somewhere. What script are you using?