I have read all about this in other threads and I have everything set to HTML, not RTF. I cannot understand why Outlook 2010 cannot handle attachments properly.
To prove this point, I sent myself a message with an image attachment using Eudora in HTML format (yes, old but reliable and robust email client), and I received it in Outlook 2010 with attachment, fine.
I then forward this same message back to myself (attachment included) and picked it up in Eudora again, but the attachment is missing replaced with this annoying winmail.dat file attachment.
After purchacing Office 2010 Home & Business, I was going to give Outlook a really good try as my only email client but becuase of this apparent "flaw" in Outlook, I am going to stick with my tried and true Eudora Pro 7 unless someone can tell me how this annoying attachment problem in Outlook 2010 can be remedied.
This all came to light when I was forwarding a message I received in Outlook 2010 with a Word document attached and forwarded it onto 4 other friends and all they received was the winmail.dat file. Very annoying.