I'm running Windows 10 64-bit. Periodically (maybe daily?), I get the below dialog appearing on my machine.
I normally just click OK and move on. This time, I ran Process Explorer, then used the "Find Windows Process" icon on the dialog to see which process was involved. This took me to a dllhost.exe process. The command line for that process included, "/Processid:{3BFADDE5-09ED-42AE-8190-2E68B650CFE6}" I looked this up in the registry and I see that this is identified as CortanaMapiHelper.
1) A search online of the error message suggested doing what it says, i.e. setting the default mail association to something. I almost did this, but when this happens I am not doing anything that would be intending to send an Email. I use Thunderbird as my Email client and I am not doing anything in Thunderbird when this happens. In thinking more about it, even if this approach would remove the message, does that mean something is sending Email on my behalf?
2) Another result from searching online was an indication that dllhost.exe -could- be something malicious, but they seemed to be associated with instances that did not have a clear /Processid argument. In this case it does and clearly indicates Cortana.
3) Although I have Cortana and have used it for reminders, I really don't use it for anything else. Certainly not sending Email.
Any ideas/suggestions/etc? The dialog showing periodically is annoying, but I'm wondering if this is a sign of something worse.
Best Answer
I found this post to be useful. In short: rename the registry key for the process ID so that the DLL launch fails. You have to become the owner of the key and give yourself full control for the rename to succeed.