Outlook 2003 / Exchange Multipart Email Gotcha

We use Exchange 2003 internally, together with Outlook 2003 as an email client.

Outlook does not handle multipart emails correctly - any attempt to preview the plain text version of the email results in showing a conversion of the HTML version into plain text, rather than the text/plain alternative.

For this reason, in order to test that the plain text version of emails that are being sent out from a ColdFusion application we are developing, I have been trying to view the email within Thunderbird - which shows the plain text version correctly. I have been connecting to exchange directly using IMAP, to avoid having to use multiple email accounts.

To my astonishment the plain text version I viewed in Thunderbird was identical to the version displayed within Outlook - i.e. a conversion of the HTML rather than the text/plain version.

Eventually (after about 3 hours testing) I realised that the entire email is re-written when viewed within Outlook 2003 - and the text/plain version is discarded...

Outlook 2007 does not seem to exhibit the same behaviour...

So once again, thanks Microsoft!