Version:           1.6.2 (using KDE KDE 3.2.3)
Installed from:    Debian testing/unstable Packages
OS:                Linux

I don't want KMail to add Re: when replying to (or Fwd: when forwarding) mail because:
1) KMail is unable to handle subjects of mailing lists with "[ml-name] Re: foobar" type subject lines.
2) I write messages in several different languages.

Alternatively you could replace the horrible "X Subject Prefixes" abomination with even a half-decent system. E.g., remove the "Replace recognized prefix..." checkbox and instead add two columns, "replace" and "replacement", to the list. The former is a checkbox specifying whether to replace the matched string or not, and the latter is the replacement (which is disable if the checkbox is unchecked). Then implement it so that the first matching regexp in the list is replaced with the replacement for that regexp. E.g., you could have "Re(?:\[\d+\]|\d+|\s*): " to be replaced with "Re: " and then "(\[[^]]+\]) Re(?:\[\d+\]|\d+|\s*): " replaced with "$1 Re: ", and then perhaps as a fallback "(.*)" to be replaced with "Re: $1". If none of the specified entries match the subject then the subject is left as it is.