We're having trouble with a client who uses Exchange Server 2010 (they send email using Mailchimp, so the issue is receiving Mailchimp emails using our template).

The email we've designed has been tested in every client in Litmus and renders fine (all versions of Outlook for example), but something is happening when it hits Exchange and it's being totally mangled! Is this a known thing, as we can't find much information via Google? I can see that the email is being switched to "quoted-printable" that affects the code, but Outlook handles this OK from our research (e.g. inserting "3D" before "=" symbols). It also seems that the charset is switching to charset="Windows-1252" but again, that seems normal for Exchange. Our email loses all formatting (CSS and structure), but we can't work out why! Can anyone help us? Thanks!