Masking as Chrome made no difference, but your tips led me to discover the issue was with Opera tracking protection. After adding an exception for https://login.proofpoint.com/ the problem resolves. Hopefully, this helps someone else, as well. Thank you, immensely, for your shared wisdom!

Masking as Chrome made no difference, but your tips led me to discover the issue was with Opera tracking protection. After adding an exception for https://login.proofpoint.com/ the problem resolves. Hopefully, this helps someone else, as well. Thank you, immensely, for your shared wisdom!

Proofpoint seems to be having an error when trying to login and open a Proofpoint encrypted email using the Opera browser. It causes the following: "Error, There is something wrong". Unfortunately, there is no way to contact Proofpoint for assistance as the recipient of an encrypted email. Peculiarly, other browsers don't have this problem, including Chrome. I've tried clearing Opera's cache completely and turning off all extensions, as well. So far it seems like a problem unique to Opera.