[Zope] how to use #sendmail properly?

hi! i would like to use the #sendmail tag together with the smtphost-attribute (without a mailhost object!!!) to send out mails. i've got a string object called MySmtpHost and i would like to use it like this: <!--#sendmail smtphost=MySmtpHost--> but of course, sendmail now tries to send the mail to a machine called MySmtpHost without dereferencing the variable. but this is not what i want... is there a way to get my variable dereferenced inside the #sendmail tag or do i really have to use a MailHost object? thilo