emailmail.app
I used the directions referenced in many places to make Outlook the default mail application on a MAC (by going to MAIL and clicking the Mail menu – Preferences to set it).
I can not do that because Preferences is grayed out because I do not (nor am I allowed to on my work machine) have an iCloud account to reference in there or any other mail account. So what else can I do?
I have some email accounts that use S/MIME and some that use GPG. When I select to use the email address configured for GPG, GPG email signing is enabled by default. When I select to use the email address configured for S/MIME, the S/MIME email signing is enabled by default.
I had to enable some settings in the GPG preference section of Mail.app, but nothing else.
Instead of selecting "iCloud" when adding the account, try "Add Other Mail Account..." and follow the configuration steps. Repost from comment for thread closure.
Best Answer
If it's greyed out, you obviously have an Admin restriction. Your option is to get the Admin to change this setting for you. I am assuming that Outlook is the default mail client of your organization. Just explain to him/her that it's very inconvenient to have Mail as the default that always pops up when Outlook is the company standard.