how to not confirm customer email at checkout?

[psalamon]

J 2.5.11; VM 2.0.20b
My customer is having problems with her customers, who affirm that they do not receive the request for confirmation email, therefore not being able to checkout. (I have run a couple of fake registrations and everything worked ok).
She is willing to run the risk, and requests there be no confirmation of email address in the registration procedure.
How to do this?
Is there any plugin that might make the registration process smoother than the one provided by VM?
thank you
Peter