Sandy - This is very simple. There is no DNS record for "listserv.herc.com" Add a forward and reverse record to DNS to associate Listserv.herc.com with the IP address of the Listserv box. Bryan Bradsby Postmaster Texas State Government Net ============================== On Fri, 2008-12-05 at 13:15 -0500, S. Dobbs wrote: > My company uses Lotus Notes. When I send messages to internal Internet addresses that are within our DMZ, e-mail goes fine. Addresses that use an external domain return error messages. Each of these 3 are a little different. > > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > > Domain of sender address [log in to unmask] does not exist Subject: > > Sandy Dobbs > Ashland Inc. > [log in to unmask]