linux - How do I allow sendmail to send TO any address?

UPDATE 10/21/2010 5p: Ok, so sending mail does work, but not sending mail to tom@wtw3.com from this box does not. The A record for wtw3.com points to the development box, but the MX records resolve to Google's servers. Is this causing the issue? How do I tell? (Verbose mail output below)

[root@dev ~]# mail -v tom@wtw3.com
Subject: Test
Test

Cc: 
tom@wtw3.com... Connecting to [127.0.0.1] via relay...
220 dev.tridiumtech.com ESMTP Sendmail 8.13.8/8.13.8; Thu, 21 Oct 2010 17:02:05 -0400
>>> EHLO dev.tridiumtech.com
250-dev.tridiumtech.com Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN

250-ETRN
250-DELIVERBY
250 HELP
>>> MAIL From: SIZE=37
250 2.1.0 ... Sender ok
>>> RCPT To:
>>> DATA
550 5.1.1 ... User unknown
503 5.0.0 Need RCPT (recipient)
>>> RSET

250 2.0.0 Reset state
>>> RSET
250 2.0.0 Reset state
root... Using cached ESMTP connection to [127.0.0.1] via relay...
>>> MAIL From:<> SIZE=1061
250 2.1.0 <>... Sender ok
>>> RCPT To:
>>> DATA
250 2.1.5 ... Recipient ok
354 Enter mail, end with "." on a line by itself

>>> .
250 2.0.0 o9LL25mA024437 Message accepted for delivery
root... Sent (o9LL25mA024437 Message accepted for delivery)
Closing connection to [127.0.0.1]
>>> QUIT
221 2.0.0 dev.tridiumtech.com closing connection

ORIGINAL QUESTION:

I am having problems when sending mail OUT from my development server.

Unless I send mail TO a user that begins with a username that exists on my box, the mail will reject and say "User unknown".

For instance, I have a user on my dev box called "twilson". Therefore, I can send email to any address that begins with "twilson", such as twilson@blahblah.com, and it will send without any issue.

But, I do not have a user "tom" on my box, so when I go to send email to tom@blahblah.com it will reject saying:

Oct 21 10:07:49 dev sendmail[19638]: o9LE7mcV019638: < tom@localhost >... User unknown

It actually takes whatever the username of the emailing address I am sending TO is and places it on the local hostname.

Why is it doing this??? How can I correct the configuration so that I can send OUT to ANYONE?

Thanks,
Tom

Additional Info:

ADDRESS TEST RESULT:

> > 3,0 fred@teaparty.net
canonify           input: fred @ teaparty . net
Canonify2          input: fred < @ teaparty . net >
Canonify2        returns: fred < @ teaparty . net . >
canonify         returns: fred < @ teaparty . net . >
parse              input: fred < @ teaparty . net . >
Parse0             input: fred < @ teaparty . net . >

Parse0           returns: fred < @ teaparty . net . >
ParseLocal         input: fred < @ teaparty . net . >
ParseLocal       returns: fred < @ teaparty . net . >
Parse1             input: fred < @ teaparty . net . >
Mailertable        input: < teaparty . net > fred < @ teaparty . net . >
Mailertable        input: teaparty . < net > fred < @ teaparty . net . >
Mailertable      returns: fred < @ teaparty . net . >
Mailertable      returns: fred < @ teaparty . net . >
MailerToTriple     input: < > fred < @ teaparty . net . >
MailerToTriple   returns: fred < @ teaparty . net . >

Parse1           returns: $# esmtp $@ teaparty . net . $: fred < @ teaparty . net . >
parse            returns: $# esmtp $@ teaparty . net . $: fred < @ teaparty . net . >

DNS TEST:

;; ANSWER SECTION:
teaparty.net.           3600    IN      MX      5 www.teaparty.net.