[imp] problem with attachments in unicode (UTF16)

[Philip Steeman]

Hello,
when I sent a mail with imp and add a attachment in UTF16, it isn't 
base64 encoded as it should be.
So it becomes corrupted when opened in Outlook or Thunderbird.

You can find a very short unicode-file here to do a test:
http://users.khbo.be/steeman/unicode.html

Is it an error in horde/imp, or in php or in ...

PS: I tested it with lots of browsers (in windows and linux) to get the 
same result.

Verions:
horde 3.1.7
imp 4.1.6
php 4.3.10

Philip Steeman