how to disable dns lookups and sendmail in sudo?

I wrote a TCP server that needs to call an external program with root
access, so it does that with sudo.

Only one problem: sudo always does a DNS lookup on the remote host, and
some hosts don't have a valid entry, and so it returns an error like this:

failed with exit code 255 : /usr/bin/sudo: unable to lookup testbox via
gethostbyname() sendmail: Cannot open localhost:25

Also in the syslog, it prints:

Jul 26 11:06:37 testbox tcpsrv[1727]: 2004/07/26-11:06:37 CONNECT TCP
Peer: "192.168.1.3:56549" Local: "192.168.1.104:3333"
Jul 26 11:06:37 testbox sSMTP[1729]: Unable to connect to localhost:25
Jul 26 11:06:37 testbox sSMTP[1729]: Cannot open localhost:25

Also, I want to disable all email attempts by sudo (which I imagine will
just go away if DNS lookups can be disabled). Here's my current
/etc/sudoers files:

# Host alias specification

# User alias specification

# Cmnd alias specification

# Override builtin defaults
Defaults !fqdn, !lecture, !mail_no_user

# User privilege specification
root ALL = (ALL) ALL
%users ALL = NOPASSWD: /usr/local/bin/tcpadmin


--
No crazy stuff in my email. ;-)