Corporate use of gnupg

Apologies if this has already been asked.  Honestly, I did my homework and looked in the archives!

I am wanting to setup up users to use GnuPG for encrypting email, mainly for internal e-mail.

Unfortunately, the "powers-that-be" want everyone that encrypts an email to also encrypt it to the "corporate secret key".  Their reasoning is that if a person leaves, they want to have access to the old emails in case there is a "business critical" email in there.

Is there a way to "force" users to encrypt to a corporate key, in addition to the receipient's key?

Thanks,

TK