After forwarding an encryptes memo, Body field is no longer encrypted

User A sends an email to User B and encrypts it.

All is fine, user C (who is the PA of User B and has access to B’s email DB can’t see the contents of the message)

User B forwards the email to user C, the forwarded memo is NOT encrypted. User C receives the email and can read it, as you would expect.

What is unexpected is that now anyone with access to user B’s email DB can now read the Body of the original encrypted email!

Forwarding has removed the encryption. Users accessing the original memo still get the warning about some items being encrypted, but the Body field is now fully readable, whereas before forwarding the email it was encrypted and invisible.

Anyone have an explanation for this behaviour?