Outlook 2016: Multiple accounts, certificates only for one
The short answer I believe is no. This is setting is a profile setting, so all mail accounts on the same profile will inherit it. You could setup different profiles for each account, but that will require you close and restart outlook to access those accounts.
Two other methods that may work:
- VBA/Macros - Use these to create messages withs specific settings applied
- Outlook custom message templates. I did look at the available fields but didn't notice any for SMIME. I don't really use custom template so may have overlooked it or it may need to be implemented or access in some other way.
I've been trying this problem for quite some time now. I even contacted microsoft support to check if they have any information on how to solve this. So their and my answer after investing an almost stupid amount of time is: There is no solution for this currently!
Since I cannot accept "no solution" answers concernig this problem, I developed an outlook addin which makes it possible to configure this and solve this problem for now. Its not completely finished yet but I'll put the source in a git repository as soon as im finished. I'll post the link down below.