Most &quot;Security Experts&quot; are working for consultancy, tech firms, and government agencies so they probably use plenty of other clients.
The majority will probably run Outlook since Exchange is the defacto mail-server standard for any organization (that isn&#x27;t tied to Lotus because 45 years ago the CEO had to sacrifice a goat to appease IBM to spare his 1st born), the rest will probably use Gmail or any other web-based mail that their smaller company is using.
Most &quot;experts&quot; don&#x27;t necessarily follow their own advice just as alcohol, drug use and smoking is more common in Doctors than any other diploma based profession out there, so can security &quot;experts&quot; run just as much as a shitty setup as everyone else and think that slightly better common sense and opsec will keep them safe which more often than not it would.