I have no experience with KDE and wouldn't try it on current old computer,
Cx486DX2-S at 66 MHz, 20 MB RAM, but might want to try KDE and/or GNOME on a new
computer, mainly for the included applications.  I feel more at home with a
command prompt than a graphic interface.  But I wouldn't reject NetBSD just
because of KMail not working right.  I think you could send mail with a Perl
script, or maybe with sendmail.  mailx?  Pine?  Mutt?  Emacs Gnus?

Reason why I haven't installed NetBSD on this computer was because it rejected
me, rather than the other way around.  Booting the installation diskettes, or
installation or generic images with DOSBOOT, hung every time (1.5.1), same with
1.5 (generic with DOSBOOT, only).  I downloaded generic kernel for 1.5.2 to try
with DOSBOOT but haven't tested it yet.  I reported my problems on port-i386 list.
OpenBSD floppy29.fs booted OK but would not recognize my CD-ROM for lack of the
needed SCSI support (Trantor T130B).

If you (Gan Starling) can't get NetBSD to work right, there is also OpenBSD as
well as FreeBSD.  I think you can even download versions of QNX, Solaris and
BeOS for i386.  There is also Serenity Systems' (http://www.serenity-systems.com)
eComStation (http://www.ecomstation.com which site uses a lot of Javascript),
which is the successor to IBM OS/2 Warp 4.

Are you unable to send email messages > 2K characters throughout NetBSD
applications?  What about other OSes?  I am not so limited, and the only OS
currently installed and running on this computer is DR-DOS 7.03.  Modem is 56K.