First, thanks for all who put their time into this project.
Seoncd, A roundcube user (IE v7.0) at my business sent a 25.1 KB Excel (.xls) file using Roundcube to 4 users:
User 1 - Outlook 2000
User 2 - Outlook 2003
User 3 - Outlook Express v6
User 4 - Outlook Express v6
All 4 users using pop3/smtp via a third party webhosting service.
Both users 3 and 4 received a 25.1 KB file that opened without trouble.
Both users 1 and 2 received a 23.4 KB file that when trying to open gives an error "The file is in a different format than specified by the file extention" and upon opening is filled with jibberish such as "?>"
The same test was tried with a Word (.doc) file and experienced the same results.
The files can be opened by all 4 users when transferred via outlook to outlook without using Roundcube.
I'd have to imagine that there is some problem with the format that extentions are being sent with when it comes to Outlook receiving them. The strange part is, Outlook Express works correctly.