I deal with a couple organizations that use CRES for external emails. The sender sends an HTML attachment via regular email. Opening the attachment goes to a login screen and displays the message after the user enters credentials. I can open the attachment using Edge or Chrome but not Firefox. After I enter credentials in Firefox, I just get a screen showing the word "Error". Has Mozilla looked at this problem and is there a solution, or should I just use the other browsers for these messages? Thanks, Ken.