[Zope] DTML Sendmail Error

[Zope@Stylus]

HI all
I am working on mandrake Linux 8.2,Zope-2.5.1
I am trying to use a dtml-sendmail tag to send a mail .But everytime I try I
keep geting the same error.Please help me out.
Where am I going worng?What len() is being asked for??

 Zope has encountered an error while publishing this resource.

Error Type: TypeError
Error Value: len() of unsized object

Traceback (innermost last):
  File /Users/zope/Zope-2.5.1/lib/python/ZPublisher/Publish.py, line 150, in
publish_module
  File /Users/zope/Zope-2.5.1/Products/Localizer/__init__.py, line 65, in
new_publish
  File /Users/zope/Zope-2.5.1/lib/python/ZPublisher/Publish.py, line 114, in
publish
  File /Users/zope/Zope-2.5.1/lib/python/Zope/__init__.py, line 159, in
zpublisher_exception_hook
    (Object: Test)
  File /Users/zope/Zope-2.5.1/lib/python/ZPublisher/Publish.py, line 98, in
publish
  File /Users/zope/Zope-2.5.1/lib/python/ZPublisher/mapply.py, line 88, in
mapply
    (Object: send_a_mail)
  File /Users/zope/Zope-2.5.1/lib/python/ZPublisher/Publish.py, line 39, in
call_object
    (Object: send_a_mail)
  File /Users/zope/Zope-2.5.1/lib/python/OFS/DTMLDocument.py, line 127, in
__call__
    (Object: send_a_mail)
  File /Users/zope/Zope-2.5.1/lib/python/DocumentTemplate/DT_String.py, line
473, in __call__
    (Object: send_a_mail)
  File /Users/zope/Zope-2.5.1/lib/python/Products/MailHost/SendMailTag.py,
line 116, in render
    (Object: MailHost)
  File /Users/zope/Zope-2.5.1/lib/python/Products/MailHost/MailHost.py, line
156, in send
    (Object: MailHost)
  File /Users/zope/Zope-2.5.1/lib/python/Products/MailHost/MailHost.py, line
201, in _send
    (Object: MailHost)
  File /Users/zope/Zope-2.5.1/lib/python2.1/smtplib.py, line 479, in
sendmail
  File /Users/zope/Zope-2.5.1/lib/python2.1/smtplib.py, line 361, in mail
  File /Users/zope/Zope-2.5.1/lib/python2.1/smtplib.py, line 122, in
quoteaddr
  File /Users/zope/Zope-2.5.1/lib/python2.1/rfc822.py, line 475, in
parseaddr
  File /Users/zope/Zope-2.5.1/lib/python2.1/rfc822.py, line 520, in
getaddrlist
  File /Users/zope/Zope-2.5.1/lib/python2.1/rfc822.py, line 528, in
getaddress
  File /Users/zope/Zope-2.5.1/lib/python2.1/rfc822.py, line 508, in gotonext
TypeError: (see above)

Thanks to all in Advance
Best Regards
John


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.476 / Virus Database: 273 - Release Date: 4/24/2003