Comment 2 for bug 527650

The error happens because there is an invalid address (Try to send to the address '<email address hidden><email address hidden>'). When I remove this address and I send again the newsletter, the error doesn't happen.
The S&D email checker accepts address like '<email address hidden><email address hidden>'; I add the Plone email checker to prevent it.

Version of zope.sendmail: 3.5.1
Traceback:
    2010-02-24T17:35:09 ERROR Zope.SiteErrorLog http://localhost/plonesite/@@dancing.utils/tick_and_dispatch
    Traceback (innermost last):
      Module ZPublisher.Publish, line 125, in publish
      Module Zope2.App.startup, line 238, in commit
      Module transaction._manager, line 96, in commit
      Module transaction._transaction, line 395, in commit
      Module transaction._transaction, line 503, in _commitResources
      Module zope.sendmail.delivery, line 93, in tpc_finish
      Module collective.dancing.composer, line 428, in send
      Module zope.sendmail.mailer, line 72, in send
      Module smtplib, line 695, in sendmail
    SMTPRecipientsRefused: {<email address hidden><email address hidden>': (501, '5.5.4 Invalid Address')}