Hello! We are using Netsuite CRM and have Email Case Capture enabled:

It is not assigning the alternate email to a contact for some reason. I ran a test with my own business & personal email. You can see here is my contact record:

and the alternate email field indicates that email capture should automatically assign the case to the contact when matching on the Alternate Email Address:

So I sent an email from my account:

And received the automatic case notification to my personal email:

But it does not associate the case with my contact or company:

Case capture does assign the contact using the primary email, however, because when I send from my primary email: