Version:           1.9.1 (using KDE 3.5.2, Gentoo)
Compiler:          gcc version 3.4.5 (Gentoo 3.4.5-r1, ssp-3.4.5-1.0, pie-8.7.9)
OS:                Linux (i686) release 2.6.16-gentoo-r1

This is only about the text of an error message which told me to file a bug here.  It's actually the same bug as 66604; I tried to send a mail with 8-bit chars over a mail server which doesn't offer 8BITMIME.  And KMail told me:

"Sending failed:
Unknown error code 50
Your server does not support sending of 8-bit messages.
Please use base64 or quoted-printable encoding.
Please send a full bug report at http://bugs.kde.org.
The message will stay in the 'outbox' folder until you either fix the problem (e.g. a broken address) or remove the message from the 'outbox' folder.
The following transport protocol was used:
Foo"

So, the error message is misleading because KMail actually knew what was wrong and thus shouldn't tell people to file a bug :)