After nosing around in rfc2231, and playing with a few problematic
clients, I have found that the rfcs permit (by means of omission) both
filename* and filename attributes to the Content-Disposition header.
Doing so causes file attachments to retain their filenames in both good,
rfc2231 compliant clients such as Netscape, and non-compliant clients such
as Microsoft Outlook.
I have modified attachments.c to include both of these attributes to that
header. Diffs for this are included in the attachment. This patch is
sub-optimal, and shouldn't be considered anything but a temporary
workaround. Specifically, for plain text attachments two filename
attributes will appear in the Content-Disposition header (instead of
filename and filename*). The patch also doesn't properly %hex encode
filenames, instead replacing problematic characters with the _ character.
This is consistent with the distributed code.
If you install this patch at your site, it may break things all to heck.
The version I am using is the 20021026 release from Double Precision.
Your version may (will) differ. If the patch doesn't work, you may assume
that it's because I'm an incompetent clod, not any fault of the actual
courier development team. You have been warned.