[imp] attachments becoming unusable

[Philip Steeman]

Hello,
I have the following problem with some kind of attachments:
- .rdp (remote desktop)
- .sav (SPPS)

The best way to reproduce the problem, is the following:

1) make a rdp-file (via remote desktop on windows)
2) mail it to yourself from imp
3) read your mail via another mailclient (Outlook, Thunderbird)
4) save this attachment via Outlook/TB
5) make a diff between the original one and the second one --> they 
differ and become unusable

The following is true;
sent with imp, saved with imp: OK
sent with Outlook/TB, saved with Outlook/TB: OK
sent with Outlook/TB, saved with imp: OK
sent with imp, saved with Outlook/TB: WRONG

Sent with TB the attachment is base64 encoded. Sent with imp it is 
'pure' text.

This is a bit annoying for our users. I tell them to zip the file first 
(or use imp to read).

The version we use:
horde: 3.1.6
imp: 4.1.6

Thanks in advance

Philip