TestFlight Access Code for External Users

One of our defense customers have policies in place to disable receipt of hyperlinks in their email. They have indicated they are not allowed to remove the policy that enforce the no hyperlink access. Consequently, when they open the Testflight application, they are prompted for the access code - where the access code is contained within one of the hyperlinks in the invite email sent by TestFlight.


Is there any way to provide the access codes directly to the customers?