When an email thread builds up to multiple replies Outlook displays the old mail in the thread in a single character column. Its pretty hard to describe without posting a picture but to illustrate a text like "this" would be displayed as:

t

h

i

s

And the text "On November 6th 2012 Joe Bloggs wrote" displays as

O

n

N

o

v

e

m

b

e

r

6

[well you get the idea].

The same email viewed from Mail.app displays just fine. As does webmail.

What am I doing wrong?