Version:            (using KDE 3.5.8)
Installed from:    Debian testing/unstable Packages

I'm trying to send a GnuPG-encrypted SSH key which I insert with "insert file". The SSH public key format is "[bytes] [key] [owner]" and these three parts get split by kmail with a line break. This makes the GnuPG signature invalid.
SMTP mandates a line limit of 998 characters, and recommends one of 78 characters for human-readable mails since some mail clients don't support soft-wrap for displaying text. But this mail is only read by an account bot. Therefore, kmail should ask whether it's ok to break the text into pieces. Considering that the middle part (the key) is the longest part, the line breakage doesn't really help anyway for user readability.

The workaround was to save the mail, edit it with vim (just removing the two line breaks), and saving it under some obscure file name into the outbox folder since kmail's "open mail" doesn't support send actions.