Version:           kdepim-4.4.2-1.fc13.x86_64 (using KDE 4.4.2)
Compiler:          gcc-4.4.3-4.fc12.x86_64 
OS:                Linux
Installed from:    Fedora RPMs

Forwarded from https://issues.kolab.org/issue2524 which is already fixed in the e35 branch:

Looking at an email having the following header:
From: "foo bar \[baz\]" <foo.bar@example.com>

In the message list the backslashes and quotes are not shown (good), but in the
message window the quotes and backslashes are still shown. At least the
backslashes have to be removed according to RFC2822:

   Where any quoted-pair appears, it is to be interpreted as the text
   character alone.  That is to say, the "\" character that appears as
   part of a quoted-pair is semantically "invisible".
...
   Semantically, neither the optional CFWS outside of the quote
   characters nor the quote characters themselves are part of the
   quoted-string; the quoted-string is what is contained between the two
   quote characters.  As stated earlier, the "\" in any quoted-pair and
   the CRLF in any FWS/CFWS that appears within the quoted-string are
   semantically "invisible" and therefore not part of the quoted-string
   either.