Can't read crypted mails

Hello

I can't read crypted Mails.
The digitiale Ids are correctly save to the contact.
The other contact can read my crypted mails, which
i send him.
But i can't read his crypted mails for me.
Also i can't read my send crypted mails to him
in my mail-folder "send message".

The error in the mail-text (translate from german to english):

"Error by decoding message.
You can't read this message."

I must install a software or set an Option ?

Thanks


Greets Sven

Hello

I have become an answer from trustcenter to this problem.
It's a problem of Windows-Mail with read the ID, which was installed in the
ie7.

The Solution for this problem:

1. export the certificate from ie7
2. import the certificate in firefox
3. export the certificate from firefox
4. import the exportet certificate from firefox in ie7

then i can read all messages in Windows Mail.


Greets Sven