How do I tell mail (or pine, or whatever) that the piped in file is html?

I'm writting a cron job and first it generates a HTML file, then grabs a list of email addresses and fires them to the people...
I've been testing with the command line using: mail someone@somewhere.com -s Subject < file.html

But once I look at it, it comes through as plain text not html. I've added a <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> as the first line of my html file and still no go.

Is there some kind of command line flag to specify the file's mime type?

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At this point I have some sample code that should allow me to talk straight to the SMTP daemon via sockets, and through some telnet testing it looks like I have the mail headers down for sending the file as html to multiple recipients.

Thanks in advance.

have you looked at uuencode.....it may help?