Email to external(trusted user) not require verify user Identity(with Google or One-time passcode)

Dear Expert and Community,

I am starting with MS Purview - Data Loss Prevention. I have one point to clarify and seek your advise / comment / contribute or sharing good practice regarding with below:

- Firstly, we can send email to externally user contain sensitive information, it is encryption or blocked (result: worked as expected). If remail encrypt, the external receiver require verify the Identity via sign in with google acc / with a one time password.

- Second: we plan sending email to external user (only trusted user / domain). Is it possible, do not require these scope user reverify their Identity again and again? If yes, how to do it? If not - why?

Well appreciated for update and supporting.

Thanks,