Can't send mail from my machine:

[Matt Miller <mmiller@tigris.netnet.net>]

The following attempt to contact the outside world fails:

    mail -s test mmiller@netnet.net < /dev/null

I immediately receive a message that includes the following error:

     mmiller@netnet.net ... transport smtp: 553 <matt@debian>...unresolvable;
     rejected. Check your DNS

All attempts to get any mail off my machine fail with similar errors.  I
called my ISP, and they offered some excuse that "Linux is designed as
a server environment, and it doesn't like routing mail through another
machine."  They suggested I either switch to Windows or Macintosh, or send
all mail by first telnetting into their network, then using my shell
account to send mail.  The latter is the technique I used to send this
posting.

I'm using smail on a hamm system, and getting a ppp connection to my ISP.
I used to be able to send mail from my machine, and I think I haven't
changed any smail configs since then.

How do tell smail to route mail through my ISP?  /etc/smail/routers is
only 

   smart_host:
        driver=smarthost, transport=smtp;

and /etc/smail/config attempts to indicate that mail should be routed
through my ISP (netnet.net) via the following line:

    smart_path=netnet.net

Thanks,

Matt Miller

-----------------------------
"Small is beautiful."
-- Mark Gancarz, "The Unix Philosophy"