At work we currently use version 3.3.3 of the Luminis III platform by SunGard Higher Education. This product handles our mail and portal needs for the time being. While it is definitely not the best web-based mail client in the world I have seen worse.
Recently I had received a notice from a friend that he couldn’t read my signed e-mail in the web-client. After having him forward the message to me as an attachment, I determined that the problem had to do with my digital signature.
I use Apple’s Mail client for OS X 10.5. Currently I also have GPGMail by Stéphane Corthésy installed so that I can seamlessly use my GPG keys to sign and encrypt my e-mail. After sending an unsigned message and finding out that it went through with no problems, I started investigating the options provided by GPGMail.
It turns out that I had checked the option to use OpenPGP/MIME by default. Apparently this creates an message body that the Luminis III web-mail client can’t read. So if you are running into this problem with a web-based client, check to see if your messages are going out as OpenPGP/MIME.