26 January 2011 by Web Bureau
This error message will occur when there is an invalid email address in the App_Data\Newsletter.xml file. This XML file contains email addresses of people who have signed up for the Newsletter (via the Newsletter widget). When you save a post, all the people in that file are sent an email. If an invalid email address exists, it will throw this error message.
If you remove any invalid email addresses from this XML file you may need to restart the blog for your changes to be detected. To restart the blog, simply modify the web.config file (e.g. add a space).