Plone forms can't send e-mail

When I fill out a form in plone 3.3.3 and try to send it i get the following error:

Traceback (innermost last):
   Module ZPublisher.Publish, line 119, in publish
   Module ZPublisher.mapply, line 88, in mapply
   Module ZPublisher.Publish, line 42, in call_object
   Module Products.CMFFormController.FSControllerPageTemplate, line 90, in __call__
   Module Products.CMFFormController.BaseControllerPageTemplate, line 26, in_call
   Module Products.CMFFormController.FormController, line 384, in validate   Module ZPublisher.mapply, line 88, in mapply
   Module ZPublisher.Publish, line 42, in call_object
   Module Products.CMFFormController.FSControllerValidator, line 58, in __call__
   Module Products.CMFFormController.Script, line 145, in __call__
   Module Products.CMFCore.FSPythonScript, line 140, in __call__
   Module Shared.DC.Scripts.Bind开发者_开发问答ings, line 313, in __call__
   Module Shared.DC.Scripts.Bindings, line 350, in _bindAndExec
   Module Products.CMFCore.FSPythonScript, line 196, in _exec
   Module None, line 20, in fgvalidate_base
    - <FSControllerValidator at /werknet20/fgvalidate_base used for /werknet20/formulieren/ideeenbus>
    - Line 20
   Module Products.PloneFormGen.content.form, line 589, in fgvalidate
   Module Products.PloneFormGen.content.form, line 630, in fgProcessActionAdapters
   Module Products.PloneFormGen.content.formMailerAdapter, line 491, in onSuccess
   Module Products.PloneFormGen.content.formMailerAdapter, line 888, in send_form
   Module Products.SecureMailHost.SecureMailHost, line 166, in send
   Module Products.MailHost.MailHost, line 144, in send
   Module Products.SecureMailHost.SecureMailHost, line 276, in _send
   Module Products.SecureMailHost.mail, line 132, in send
   Module smtplib, line 683, in sendmail
   Module smtplib, line 453, in rset
   Module smtplib, line 378, in docmd
   Module smtplib, line 355, in getreply
SMTPServerDisconnected: Connection unexpectedly closed

Any idea what the problem could be? The smtp is configured correctly ( or so they say ).

Thanx!

As the traceback indicates, this is a problem with your SMTP server, not Plone. It is most likely refusing the sender.

The last few steps show that Python's smtplib module managed to connect successfully to your server, as the sendmail call only is executed if the server has already accepted the credentials.

The fact that smtplib then tries to send a RSET means something did go wrong with the MAIL FROM command; generally this means that the sender was refused. Your SMTP server then rudely closed the connection, not bothering to wait for a QUIT.

You'll need to look into your SMTP server configuration to see what would make it accept your sender.