[Closed] Exchange 2003/Outlook - HTML email arriving unformatted? randomly?

Hello,

Got a bit of an issue and I wondered whether any of the kind IT types here would be able to shed some light?

SBS2003 / Exchange box, mail comes in via maildistiller and out to webmail/outlook 2007.

Occasionally (moreso than not) html email arrives unformatted so all the tags are visible and it is illegible, this doesn't happen all the time though as some mail arrives (from the same source, so ebuyer, maplin, mail distiller etc) sometimes can be viewed and sometimes not - using either webmail or on the client.

I've looked on the exchange box and it's set to MIME & "both" html&plain text and set to "western european (iso-8859-1)"

Any thoughts as to where to start investigating would be very much greatly! Appreciated!

jt