Sep 14, 2021
Most email clients support S/MIME, such as Outlook, Thunderbird, Apple Mail, Lotus Notes, and Mulberry Mail. For a detailed summary of S/MIME compatibility between email clients and S/MIME best practices, please see our S/MIME White Paper.
Additional Resources:
S/MIME White Paper: https://www.globalsign.com/resources/white-paper-smime-compatibility.pdf
Check your certificate installation for SSL issues and vulnerabilities.