I am working on a testing tool and the testing tool asks the user to insert the user certificate in cert format like test.cert format and sends an encrypted attached file to my email id. Once I have received the file I want to download that file and decrypt the file. The file which I receive is named as smime.p7m and I am using p7mviewer to decrypt that file. But the tool is sending a message that the "The private key is not installed in the system". But when I use my own php script and send an encrypted email to my account the p7mviewer is able to decrypt that email. Can anyone tell me what I am doing wrong. From my php script I am not sending an attachment but I am sending an encrypted message to user's email.
Thanks in advance