Michael,

You need to have your DNS people remove the MX records that point mail
bound for listserv.opm.gov to other servers.  If they must have an MX,
it should point to listserv.opm.gov in order that LISTSERV mail can go
straight to the LISTSERV machine.  If listserv.opm.gov is behind a
firewall (as it appears it may be) then you need to have the people in
charge of the firewall open port 25 access to the machine so that
mail can get through.  You would also have to have them open port 2306
for the LISTSERV TCPGUI interface used by the web features, if you
have the web features enabled.

The only alternative to the above is to ensure that the machines that
are defined as MX hosts for listserv.opm.gov know what to do with mail
addressed to recipients on listserv.opm.gov.  It does not appear that
this is currently the case.  Note that there are two MX hosts and both
of them would have to be able to do this.

If you are running LSMTP you need to stop and disable the SMTPL.EXE
"listener" service as it will otherwise conflict with LSMTP.  (The
LSMTP installation should technically have done this for you...)

Nathan