target import primary email

Hi

We are trying to send out a Campaign, which tests ok, and we have imported a target list with emails.

This all appears ok but Campaign didn't send and when checking error logs the email addresses in the Targets aren't Primary Email Address.

I have looked everywhere and can not see how to set the imported email address as primary and there are over 1500 don't want to update them manually.  Does anyone know how to import emails into Targets and set them to Primary or send a Campaign using any any email from the Target.

Can this be done via mass update?

Using 7.6.2.1 Ent

Any help or pointers much appreciated.