[Zope] Sendmail Problem

[RC Compaan]

I've tried everything to get my feedback form to work, but i keep getting
this:
Recieved error code 553 from SMTP: 553 ... Domain name required.

I've tried using mailhost="MailHost" in my sendmail tag; I tried
From:<dtml-var E-mail> and ended up putting in a e-mail address explicitly
as shown below, but nothing works.

<!--#sendmail smtphost="up-front.co.za"-->
    To:roche@bluelagoon.co.za
    From:roche@bluelagoon.co.za
    Subject: Feedback from BlueLagoon Website

    Feedback from : <!--#var Surfername-->&nbsp;<dtml-var Surfersurname>
    Comments:
    <!--#var txtMessage-->
<!--#/sendmail-->

Please help

Roché Compaan