After updating your computer (particularly to Mac OSX Yosemite) you may find that one or more of your browsers (Chrome, Firefox, Safari) won't allow you to access your Zmail, saying that the site is untrusted.
If any of your computer's browsers are preventing you from accessing zmail, follow these steps to prevent further issues:
1. Right click the following link and click "Save Link As" OR click on the attached file to download it.
2. When the file is downloaded, double click it. If prompted to "Add" the certificate in Keychain Access, click "Add" or "OK"
3. In the Keychain Access application window that opens, navigate to "Equifax Secure Certificate Authority" and right click it.
4. Click "Get Info"
5. Click on the small arrow next to "Trust" near the top left.
6. In the dropdown for "When using this certificate" select "Always Trust"
7. Enter your password as needed to modify the certificate.
8. Reload the website.