Email not arriving

I am trying to replace Adobe's Developer Toolbox email functions on various forms with the Contact Form Solution Pack. However, though I can send forms by email using Adobe's DT those from the CFSP never arrive. The CFSP form works perfectly and moves to the 'thank you' page without any problems. I have checked my SPAM folders and the forms are not getting caught there.

I assume the issue is with the mail settings. Those that work in Adobe's DT are:

$tNG_email_host = "localhost";
$tNG_email_user = "";
$tNG_email_port = "25";
$tNG_email_password = "";

I have put $WAGLOBAL_Email_Server = "localhost" ; in the 'WA_Globals.php' file and in the 'WAUE_contact_1.php' file there already was the line:

$WA_MailObject = WAUE_Definition("".($WAGLOBAL_Email_Server) ."","25","","","","");

I presume that this is what I must tinker with, but how do?

Thanks,

Steven.