There's a 30 day trial viewer at the link below:
Or Googling ".p7m Viewer" gets you a lot of hits.
Hope this helps.
I hope this is the correct forum. I have obtained and installed a security certificate for my work email and my home email. I chose to use a free Comodo certificate for each, though I don't think that matters to the discussion. I'm running Thunderbird 3.0.3 (though I see that the update is downloading while I post) on Win 7 Pro.
My employer uses an undocumented 'secure email' application for Exchange Server that is enabled whenever the word 'secure' appears anywhere in an outgoing email's subject line. The application sends the recipient a notice about a secure email. To view the actual message, the recipient must log on to a web page that uses an invalid security certificate to view the email (the security cert is a separate problem). I can do all that when required BUT I can also send myself secure, signed email from work using Outlook's encryption capabilities if I use the security certificates I have installed.
The other day I had to create a new password while at work so I sent myself an encrypted email with the valid login credentials from a web site. I encrypted the email at work and sent it with a subject line something like: 'Information for XXXXX secure site' thus accidentally invoking the employer's undocumented secure email feature.
Here's the problem. When I go to the secure web site, my encrypted email is presented as a web page, not an email. The smime.p7m file that Outlook sent in the encrypted email is available for download, but once I download it I have no idea what to DO with it. As best I can tell, Thunderbird will only open this type of S/MIME file as part of the process of decrypting a secure email.
IOW, once the S/MIME attachment exists as an isolated file, no longer associated with an email, there is no obvious way to open it. So, is there some other way of opening it?
In this case it's no huge deal. Once I found out what triggered the 'secure email' system at work I just sent the message out again as an ordinary signed/encrypted email, but there will be times when I may need to know how to open the smime attachment because it will not be convenient to go back to work and send it again.
I have asked the IT folks to consider whether there is a way to set the system up so that it does not encrypt messages automatically when they have subject lines like:
'Is there a way to secure permission to ...'
I don't know what they will do about that. I also don't know if they will fix the security certificate problem. But those are other problems. For now, I'd just like to figure out if there is any way to open the smime.p7m file if the problem recurs.