How can this code be adjusted to use php mail instead (or force it with some other method)?

Hey folks,

I was getting this regarding the mandrillapp plugin (to allow it to handle all emails via smtp):

Mandrill: wp_mail has been declared by another process or plugin, so you won't be able to use Mandrill until the problem is solved.

We identified the offending plugin:

What changes could be made directly to it to force it to use mail php instead of wp_mail so the error will disappear and we can use mandrillapp plugin afterwards?

Or, is it simply a config.php setting we could force?

I have enabled support access as well via wpmudev. The site is:

***When you login, you will see the mandrillapp plugin error.

Please let me know what you think...