How to add S/MIME certificate to samsungs native email app on galaxy s3 In my Android 4.3 Samsung Galaxy S3 there is a builtin Email App. If i open the account configuration there is an option to sign outgoing emails.

Configure Email Account > Security Options > Sign outgoing Emails (check)

Below is another item called PRIVATE KEYS.
If i open it, it shows an empty page. I can click Menu>Import Key and it shows me another empty page. 

I have S/MIME certificate signed by a trusted root CA (StartCom) and i copied it via USB to my phone. The file is a "filename.p12" file maybe this is the problem but it worked for outlook on my computer.

How can I add my private key to my email accout to be able to use the "sign outgoing emails" option?

Please help me, i am struggeling around since hours. It cannot be the case that nobody used this option before.
After a long time of researching I found this useful link:

http://www.gridshore.nl/2013/09/30/setting-up-keys-to-sign-emails-in-samsungs-android-email-app/

It seems to be the case that it is not trivial to make android to find the keys. You need to place them in a special folder with a special filename. 

But the worst is that samsungs email client supports S/MIME only for exchange connections and not for pop3 or imap. I cannot imagine why this is the case but it seems to be true.

All of that makes me belive that some people dont want us to encrypt or sign our emails. What a shame!