Apparently Japanese language Internet Explorer (I believe) is unhappy with SquirrelMail 1.4.0, so I made the old version (1.2.9) available under the /squirrelold URL.

Some students in Japan complained that they were getting blank pages upon initial connection to the SquirrelMail login page. This corresponded with the introduction of 1.4.0, so after determining that it was the Japanese browser and that I couldn't really debug it at present, I enabled the /squirrelold URL (primarily accessible from the root webmail server page). Reports are that this works.