The extension seems to be working, but could you please look after these warning and error messages:

Warning: eZTemplate:undef @ extension/cjw_newsletter/design/admin2/templates/includes/cjwnewsletteredition_preview_archive.tpl:45[0]:
Variable 'show_iframes' is not defined with

{def}.

Warning: eZTemplate:undef @ extension/cjw_newsletter/design/standard/templates/contentstructuremenu/4_newsletter_list.tpl:56[16]:
Variable 'subcripion_user_statistic' is not defined with {def}

.

Error: eZTemplate @ extension/cjw_newsletter/design/standard/templates/newsletter/subscribe.tpl:181[24]:
Unknown template variable 'node_url' in namespace ''

Error: eZTemplate @ extension/cjw_newsletter/design/standard/templates/includes/cjwnewsletteredition_statistic_list.tpl:86[20]:
Unknown template variable 'current_send_statistic' in namespace 'EditionList'

Error: eZTemplate @ extension/cjw_newsletter/design/standard/templates/content/datatype/edit/cjwnewsletteredition.tpl:16[4]:
Cannot retrieve attribute of a NULL

Error: eZTemplate @ extension/cjw_newsletter/design/admin2/templates/includes/cjwnewsletteredition_preview.tpl:15[0]:
Unknown template variable 'output_format_array' in namespace 'ContentAttribute'

Error: eZTemplate:foreach @ extension/cjw_newsletter/design/admin2/templates/includes/cjwnewsletteredition_preview.tpl:15[0]:
Missing/malformed array to iterate through.

Warning: eZTemplate:undef @ extension/cjw_newsletter/design/standard/templates/content/datatype/edit/cjwnewsletteredition.tpl:20[0]:
Variable 'attribute_base' is not defined with

{def}

.

Steps to reproduce

I woudn't provide step by step instructions for each and every log entry as i think it's pretty obvious where is the message coming from. Basically i was clicking around in the cjw newsletter extension.