Description of Problem:

Evolution 1.4.6 mangles the multiline X-Spam-Report header that
SpamAssassin can be configured to add to messages.  The header content is
intended to line up vertically for easy reading when viewed as plaintext,
and uses tab newlines and tab characters to achieve this effect.

However, Evolution performs a paragraph reformat on the header content,
similar to what par(1) and fmt(1) do, such that carefully placed newlines
are removed and the lines broken on length.

This is not a UI bug; the header is actually mangled on disk.  I've checked
the message as stored on disk (maildir format), and the header is mangled
there too.  I have tested and found that the header is not mangled as
stored on the POP3 server, nor does the POP3 server mangle it during a
manual telnet session.

Steps to reproduce the problem:

1. Arrange for a message to exist in a POP3 account from which Evolution
retrieves mail.  Include an X-Spam-Report header in an email message.  It
should be formatted (note the tab characters) as shown at:

    http://starjuice.net/evobug/evo.good.txt

2. Fetch the message by clicking on Send / Receive in Evolution.

3. Select View -> Message Display -> Full Headers.  Note that the
formatting of the X-Spam-Report now looks more like the one shown (still
with tab characters) at:

    http://starjuice.net/evobug/evo.bad.txt

How often does this happen? 

100% Reproducible on 3 separate installations.