Email Encryption between two AD Forest by implementing internal Microsoft CA

Can we send an encryption email between two AD Forest (vice versa) by implementing internal Microsoft CA.
E.g. domain have their own Enterprise or Standalone CA and have their own Enterprise or Standalone CA
If can, how do the users for domain 'trust' the users from domain? Is that something like this: domain users need to install root certificate and domain users need to install root certificate.
Is there any requrements to do on the servers level instead of at the client PC.

Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

you can install your own self signed certificates in microsoft.  Once you have the certificates you can use that to encrypt email as long as the domain is trusted in your root domains.  If not then you just have to right click on the digital signature and trust that certificate.  

The receiver must have the public key (the digital signature you sent) and you must have theirs.  After that you can encrypt.

i usually install the certificates using the mmc snap in. pick user certificates

aihaiaiAuthor Commented:
How do I install the self sign certificate?
Can you give the steps to do on domain and domain e.g what to do on server level and what to do on both domain clients
go to this link.  it will give you step by step instructions

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Active Directory

From novice to tech pro — start learning today.