That sounds like you're sending in Rich text format to non-Outlook
recipients. That causes winmail.dat. Send in plain text or HTML format.

--
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Absolute Beginner's Guide to Microsoft Office Outlook 2003
Reminder Manager, Extended Reminders, Attachment Options
http://www.slovaktech.com/products.htm


"István Becze" wrote in message
news
I'm developing an Outlook add-in in VB using VS 2005 and VSTO 2005 SE. I
use
a custom form that creates a new MailItem and I attach a file to it by the
add-in. If my Outlook email account is configured as a POP/SMTP client,
the
recipient of the email receives a file called Winmail.dat instead of the
attachment. Interestingly, if the Outlook email account is setup as an
Exchange server client, then the attachment is received correctly by the
recipient.

How can I achieve the attachment to be sent correctly over an SMTP server?
Any idea would be appreciated.

Thanks,

Istvan