[support] drupal_mail and gmail auto response

If I send an email to a certain gmail address, then I get an autoresponse. This is good. :)

We have a custom form setup that uses drupal_mail and I use this:

$from = "$name <$email>" ;

and no reply-to or anything like that. When I use the form to send an email, I see that it goes to the correct gmail address (same one as above that is), but no autoresponse is sent. Yes, I used a different email then the first email I sent b/c the responder won't respond more than twice in four days. I wonder if the issue is that the gmail address is not gmail.com--it's actually the same domain as the site--they use a Google App for email. Maybe gmail sees that it's internal yet the purported email address is external?

Any other ideas why this may be failing?