I have a script that sends encrypted emails.  It uses GPG to do the
encryption.  It uses "sendmail -t" to send the message.  Most people
get the message and can easily decrypt it in their email clients.  But
one guy always sees the message as an ATTACHMENT.  He is using an
email client called "SecureBat!" I think.

What magic incantation do I need to include in the chunk of text I
pipe into sendmail to avoid this problem?