Mail me when someone runs sudo
This is straightforward; Defaults can apply to specific users (and other limitations), and user aliases can be constructed with negated matches. Something along these lines:
User_Alias NoMail = goodboy, goodgirl
User_Alias MailUsers = ALL, !NoMail
Defaults mailto="[email protected]"
Defaults:MailUsers mail_always
Defaults:NoMail !mail_badpass