Currently I am setting this module up as multi-tier. Auth.Net is working PayPal is not (see support ticket). However in either case the emails are not being sent upon registration. I know the email server is working and I know that the from address is valid as other modules are using it.

Any thoughts?

The host/admin setting are working for all other aspects of the site. So those settings are correct. The address used in the registration module is not the same as the admin. Does the Mail From email address have to match the admin account?

Will do some more testing as obviously the sending of emails is important.