I am trying to send a file that does not have an extension to a recipient.
Is this possible with Outlook?

The recipient typically receives the attachment renamed to attachment.dat.
I've tried turning off the "Always send messages in Microsoft Exchange rich
test format". Now, the recipient's client software typically saves the file
as attachment.txt.

Other than zipping the attachment file, is there any consistent way of
getting a file through without an extension?

--
Gerald Boutin