Sending encrypted emails from the iPad is not working

Question

I can't get sending encrypted emails working on my iPad3 running iOS 8.0.2
Let me explain what I did:
1. I created S/MIME certificates for 2 email addresses on my iMac in Keychain Access. One email address exists only on the iMac the other only on the iPad.
2. I set "When using this certificate" to "Always Trust" in both certificates.
3. I exported 1 S/MIME certificate (p12) and installed it on the iPad. Then I deleted this certificate and its private&public keys in iMac Keychain Access
4. I exchanged public certificates between the 2 devices. I installed one certificate in iMac Keychain Access and the other in iPad/Settings/General/Profiles.
5. On the iMac in the iPad certificate I set "When using this certificate" to "Always Trust"
6. I tested whether I can send and receive signed and/or encrypted emails
Results:
1. From the iMac I can send signed and/or encrypted emails to the iPad.
    On the iPad I can read the encrypted emails. The signature is not trusted
2. On the iPad I can send signed messages to the iMac. On the iMac the signature is trusted.
    I cannot send encrypted emails from the iPad to the iMac. The iPad doesn't know about the public certificate in iPad/Settings/General/Profiles
So much for the straight forward part. Now it gets a bit more complicated and confusing.
1. I deleted the iMac certificate in the iPad/Settings/General/Profiles. Then in iPad Mail I opened the signed mail coming from the iMac.
    I viewed the untrusted certificate in Mail and installed it. From this point on all signed emails from the iMac are trusted.
    Strangely the by this method installed certificate doesn't appear in iPad/Settings/General/Profiles.
    Furthermore I still cannot send encrypted messages to the iMac. This certificate installation seems to be used only to check trust worthiness of the signature.
    Installing on top the iMac public certificate in iPad/Settings/General/Profiles doesn't enable to send encrypted messages from the iPad either.
To be sure that this problem relates to the iPad certificate management and is not related to an error by me I did the following:
1. I transferred a p12 file for a certificate that I created in my iMac to a PC running Windows7.
2. I transferred a p12 file plus its public key (.pem) that I created in my iMac to another iMac into Keychain Access. (I have not tested if the pem is needed).
3. On the other iMac and the PC I made sure that the certificates are trusted.
    On the PC that means in the Certificate Manager the p12 needs to be in the "Personal" folder and in the "Trusted Root Certification Authorities" folder.
    The public keys need to be in the "Trusted People" folder and the "Other People" folder. One can just copy/paste the certificates.
4. In both cases I deleted the certificate and public/private keys on my iMac.
5. I exchanged public certificates between the devices.
6. I tested exchanging signed and/or encrypted emails between my iMac and the PC and my iMac and the other iMac.
Result:
1. I can send signed and/or encrypted emails to the other iMac and the PC
2. The PC and the other iMac trust the signature from my iMac and can read the encrypted emails
3. My iMac can read encrypted emails from the PC and the other iMac
4. My iMac trusts emails with signatures from the PC and the other iMac.
Everything is working as it should.
After the above test I wanted to see whether I can set up encrypted email exchange between the iPad and the PC. Strangely iPad Mail recognized the public certificate from the PC installed in iPad/Settings/General/Profiles and allowed me to send an encrypted email to the PC. However, on the PC I was unable to read the encrypted email. And the other way around, encrypted emails send from the PC to the iPad cannot be read on the iPad.
My conclusion from all this testing is that iPad mail encryption is still "under construction".

Answer 1

I was able to resolve the above described problem to some degree. Setting up sending and receiving encrypted emails between iOS and OSX I have working.
What is still not working is reading encrypted emails on the iPad/iOS8 received from Windows 7 PC. And sending encrypted emails to Windows 7 PC.
The details about how I solved part of the problem are described here.