Question : Exchange 2007 to remote non Outlook/Exchange clients. Attachment not received

I have two different sites that are running Exchange 2007 Servers under SBS 2008 (SP2). From both of these sites, if an attachement is sent, to some remote, possibly non Exchange or Outlook sites, the attachement is either dropped or a winmail.dat is received. Both of these sites have only recently been upgraded (server wise) from Exchange 2003 under SBS 2003 to Exchange 2007 under SBS 2008. Prior to the upgrade, the same clients happily sent and received all attachments. I have searched the net and EE and have attempted to apply the only answer I have found such as http://www.experts-exchange.com/Software/Server_Software/Email_Servers/Exchange/Q_23018826.html?sfQueryTermInfo=1+attach+client+non+outlook. However changing the format at my sites, client Outlook to Plain Text has had no effect what so ever, and the remote addressee still have either the attachment missing or the old winmail.dat.
At first I thought the sending Exchange 2007 server was stripping the attachement, however I have set up a test 'Remote Client' using Windows Mail on a Vista Pop client with my local ISP, through this ISP I am able to view the mail using a webmail feature. The email from the Exchange 2007 clients show the attachements (but only as a winmail.dat), However when I pop the email the attachment is not there at all.
Additionally, when I send similar emails from a different site under SBS2003 and Exchange 2003 client, the attachments are recieved, regardless of the format, plain text, rich text or HTML.
I feel there is something in the new Exchange 2007 scenario that requires changing rather than the clients.
Has anyone seen or experienced this same problem and if so, can u shed some light on the subject?
Thanks

Answer : Exchange 2007 to remote non Outlook/Exchange clients. Attachment not received

Winmail.dat is the result of an attachment sent in a mail that is formatted as Rich Text, see:
http://support.microsoft.com/kb/138053

Basically, use HTML as format, and double check that HTML is actually the format being sent.
As long as you are getting winmail.dat the mails are being sent as Rich Text.

In EMC:
# Open Exchange Management Console
# Expand Organization Configuration-> Hub Transport
# In the right pane select the Remote Domains tab
# Right click Default and choose Properties
# On the tab named Format of original message sent as attachment to journal report: you can enable Rich Text always or never or determined by user settings.

I suggest you choose Never